The new A-Class embodies the next stage in our design philosophy of Sensual Purity and has the potential to usher in a new design era,” says Gorden Wagener, Chief Design Officer Daimler AG. “With clear contours and sensual surfaces, we present high-tech that awakens emotions. Form and body are what remain when creases and lines are reduced to the extreme. The interior represents modern luxury at a level previously unattained in this class, and translates intelligent technology into an emotional overall experience.
Exterior design: Exercise in purism
The purist, surface-accentuating design of the new Mercedes-Benz A-Class is the next step in the Mercedes-Benz design philosophy of Sensual Purity. On the basis of a compact two-box design, optimised dimensions and proportions have led to a new interpretation of the Mercedes-Benz A-Class’s design.
The exterior of the new Mercedes-Benz A-Class stands for sportiness, dynamism and emotion. The progressive front design with a low bonnet, flat LED headlamps with chrome elements and torch-like daytime driving lamps ensures an emotionally appealing and alluring appearance. The striking radiator grille with Mercedes star, whose silhouette opens out towards the base as a reinterpretation of its predecessor, features pins in a diamond look and a central silver louvre to underline the sportiness of this model. The prominent air inlets in the lower area of the bumper echo the silhouette of the radiator grille.
The vehicle is visually extended by the longer wheelbase and character line along the side. The bonnet slopes down more heavily than in the preceding model series, emphasising the dynamic, upright front. The larger wheel arches for wheels from 16 to 19 inches emphasise the sportiness of the new A-Class and make it sit more squarely on the road.
The vehicle has a wider look at the rear end thanks to a more heavily waisted greenhouse, which also emphasises the shoulders, and to the wider-spaced rear reflectors in the modular, two-section rear bumper. Depending on the equipment level, the rear bumper is available with a black diffuser or, in the Progressive equipment line, with chrome trim and exhaust tailpipes. The slim, two-section tail lights ensure an emotionally appealing, alluring appearance. The spoiler in high-gloss black mounted on the side of the rear window improves the aerodynamics.
At market launch, three non-metallic and four metallic paint finishes plus the designo paint finish designo mountain grey will be available.
Interior design: A revolution from within
The interior of the new A-Class is completely redefined with its modern, avant-garde look. Mercedes-Benz has taken a completely new approach, revolutionising the compact class from the inside with a new feeling of spaciousness. The unique interior architecture is shaped in particular by the avant-garde design of the dashboard: For the first time a cowl above the cockpit has been completely dispensed with. As a result, the wing-shaped main body of the dashboard extends from one front door to the other with no visual discontinuity. The Widescreen display is completely free-standing. The air vents in a sporty turbine-look are another highlight.
The interior architecture and the control & display systems of the new A-Class are an avant-garde USP in this segment. The dashboard is divided into two three-dimensional, horizontal sections: the lower section is visually separated from the main body of the dashboard by a “trench”, and it appears to float in front of the dashboard. The optional ambient lighting enhances this effect, accentuating the free-floating impression of the substructure.
The lower section of the dashboard provides the basis for the turbine-look air vents and the completely free-standing display. This is available in three versions:
- with two 7-inch displays (17.78 cm),
- with one 7- and one 10.25-inch (26 cm) display and
- with two 10.25-inch displays.
- Integration of the air conditioning display into the central screen also considerably helps to maintain the clear line of the cockpit. The air conditioning is controlled by the horizontal rocker switches of via the corresponding touchscreen menu.
Thanks to the omission of a cockpit cowl, the main body of the dashboard with its trim extends from one door to the other behind the seemingly free-floating Widescreen. The optional trim elements are in a “wrap-around” design, and the choice of materials (e.g. open-pore wood) underlines the progressive, modern positioning as the top interior in this class.
The five round air vents have a new turbine look inspired by the world of aviation. Finely designed air vanes in a concentric arrangement create the impression of a jet aircraft turbine. In the Style equipment line the vent surround is colour-accentuated at the depth of the vent geometry, giving the impression of an afterburner. The air vents in the middle are driver-oriented, accentuating the sportiness of the interior.
The door centre panel transitions seamlessly into the armrest, underlining the sensual, flowing design principle. The newly designed 3-spoke steering wheel, door handles, centre console and seats follow a modern design idiom. The ring-shaped, completely closed grab/door-pull handle is of unusual design and particularly ergonomic.
Colour and trim: fresh colours and unusual trim
The interior can be adapted to suit personal tastes in many ways. The fresh colour concept plays an important part in this: the choice includes indigo blue inspired by the denim jeans look, as well as cool neva grey exclusive to the Mercedes-Benz A-Class. Light effects create an additional effect in this context.
Depending on the equipment line, different types and colours of trim elements are available for the dashboard. An overview of the trim elements:
- Style: colour band matching the upholstery in neva grey, indigo blue or black with integrated, contrasting piping in light blue or orange
- Progressive: carbon-fibre look in black or silver
- AMG Line: AMG DINAMICA black
- Optional for Progressive/AMG Line: light aluminium with longitudinal grain, light aluminium with line grain, trim in black open-pore lime wood or brown open-pore walnut wood
- Ambient lighting: avant-garde light pattern
From 12 to 64 – with the generation change, five times as many colours are optionally available for the ambient lighting of the new A-Class. It is not just the variety that has increased, as the emotive presentation also sets standards in this segment: the different colours are composed into ten colour worlds to allow an avant-garde lighting display with spectacular colour changes.
The colour worlds can be matched to the different styles of the widescreen display if required, creating a harmonious overall impression. There are also lighting effects that customers can activate individually.
The avant-garde ambient lighting was already taken into consideration in an early development phase, and systematically integrated into the interior design. This is apparent in the area where the upper and lower sections of the dashboard come together, for example. Thanks to a combination of indirect and direct lighting, a very special ambience is created here which might be compared to the night-time illumination of a historic building. The interior of the turbine-like air vents with galvanised surfaces is likewise emotively presented by the ambient lighting.
Driving assistance systems: High safety standard with functions from the S-Class
The new A-Class has the very latest driving assistance systems with cooperative driver support, giving it the highest level of active safety in this segment with functions adopted from the S-Class. For the first time, the A-Class is able to drive semi-autonomously in certain situations.
The new Mercedes-Benz A-Class has an eagle-eye on the traffic situation: improved camera and radar systems allow it to see up to 500 m ahead. The A-Class also uses map and navigation data for assistance functions. For example, Active Distance Assist DISTRONIC as part of the Driving Assistance Package is able to support the driver in numerous route-specific situations, and predictively and conveniently adjust the speed e.g. when approaching bends, junctions or roundabouts.
The driver is also able to see at a glance which assistance functions have been selected, and to which situations the systems are reacting at present. Clearly understood icons – e.g. a steering wheel with hands on both sides – give information both on the screen and in the head-up display. All the driving assistance functions can be operated via the steering wheel.
Active safety as standard: extended Brake Assist
The new A-Class comes with extended Active Brake Assist as standard. Depending on the situation, this can effectively help to mitigate the consequences of rear-end collisions with slower-moving, stopping or stationary vehicles ahead, and even with crossing pedestrians and cyclists, or prevent them altogether. If the distance drops significantly below the safety threshold, the system issues a visual warning to the driver. If it detects a serious risk of collision, the driver receives an additional, audible warning. It also computes the brake pressure required to prevent a collision, if this is still possible. If, having been warned, the driver then steps on the brake pedal, the system is capable of boosting insufficient braking pressure in line with the needs of the situation. In so doing, it makes the best possible use of the remaining distance in order to leave the vehicles behind room to brake. If the driver fails to respond, Active Brake Assist can go one step further and brake autonomously if the danger of collision persists, so as to mitigate the severity of the accident or in the best case even prevent it.
ATTENTION ASSIST with adjustable sensitivity, which can warn the driver in timely manner of inattentiveness and drowsiness, is also included as standard.
Modular driving assistance system: support according to preference
The A-Class offers a modular range of driving assistance systems. In addition to the already extensive standard equipment specification, optional extras right up to the Driving Assistance package also make it possible to individually configure the vehicle with respect to driving assistance. Active Distance Assist DISTRONIC is individually available for comfortable longitudinal control, and in conjunction with traffic sign recognition in the navigation system this allows manual adoption of recognised speed limits.
Already in its purely advisory version, at low speeds the Blind Spot Assist is capable of warning of vehicles, including bicycles, in the danger area. For the first time, when the vehicle is at a standstill it can signal to the driver with a visual warning in the exterior mirror before they climb out that a vehicle is driving past in the critical area. If the driver uses the door handle at this moment an additional acoustic warning sounds. The object driving past must be moving at more than 2 m / s. The function is also available when the vehicle is stationary and up to three minutes after the ignition has been switched off. Blind Spot Assist can be extended with Active Lane Keeping Assist which, already in the basic variant, is capable of warning against unintentional lane departure by vibrating the steering wheel and, if the driver crosses a solid line, of correctively intervening by means of one-sided braking action.
The functionality of Traffic Sign Assist has been extended to include, for example, a warning of pedestrians near zebra crossings, and an extended wrong-way warning function which is now not only able to warn against wrong-way entry into motorway slip roads, but can also warn against driving the wrong way into a one-way street or onto a roundabout. In addition, the detection of stop signs has been coupled with the ECO start/stop function, and is suitably taken into consideration by the latter – the engine remains on.
Driving Assistance package: numerous assistance systems usefully combined
The assistance and safety systems are grouped together in the Driving Assistance package (optional equipment).
Active Distance Assist DISTRONIC with Active Steering Assist: Within a speed range from 0 – 210 km/h, and on all types of road – motorway, country road or in urban areas – the system is not only able to automatically maintain the correct distance from the vehicle ahead, but also to give the driver noticeable steering assistance, even on bends. At speeds up to 130 km/h the system is not necessarily dependent on clearly visible lane markings, as it can also intervene actively if the lines on the road are unclear, as is often the case at road works, or even if there are no lines on the road at all. The system therefore makes driving much easier, especially in bumper-to-bumper driving or tailbacks.
The reduction in speed takes place in varying degrees, depending on the selected DYNAMIC SELECT driving mode (e.g. SPORT, COMFORT or ECO). This means that semi-automated driving for longer periods is also a reality on country roads. Active Distance Assist DISTRONIC controls the distance from the vehicle ahead within a speed range from 0 to 210 km/h, and keeps the car on track. Coasting characteristics, e.g. on downhill gradients, can now also be taken into account.
Active Speed Limit Assist: In conjunction with MBUX, Active Speed Limit Assist – an engageable subfunction of Traffic Sign Assist – is also able to recognise sign gantries and road works signs by camera. Known limits, such as 50 km/h in built-up areas or 100 km/h on country roads, are also adopted from the navigation system. Active Distance Assist DISTRONIC adapts the vehicle’s speed to the recognised speed limits automatically (in combination with navigation and traffic sign recognition). In certain cases, the speed can be adapted in anticipatory mode on the basis of map data. On roads without speed limits, such as stretches of German motorways, the recommended speed – in this case 130 km/h – is adopted as the set speed. This speed can be adjusted by the driver. The desired maximum speed is always adopted in the course of the journey when the speed limit is lifted. It remains preset until the vehicle leaves the motorway or until the engine is switched off.
Following vehicles in a tailback: in stop-and-go traffic on motorways and similar roads, stops of up to 30 seconds are now possible within which the Mercedes-Benz A-Class automatically moves off and follows the traffic ahead.
Active Lane Change Assist: When the driver wishes to change lanes on multi-lane roads (recognised by the navigation system) at speeds from 80 to 180 km/h, it is now sufficient to nudge the indicator stalk. Within the next ten seconds, the sensor system checks together with the driver whether the next lane is clear in front of, alongside and behind the vehicle, also taking into account the speed of any other vehicles. If there is no other vehicle within the relevant safety zone, the driver is supported in changing lane. The initiated lane change is indicated in the instrument cluster and on the head-up display. The system is available in certain countries, depending on certifiability.
Active Emergency Stop Assist: Active Emergency Stop Assist brakes the vehicle to a standstill in its lane if it detects that the driver is no longer actively driving the vehicle while it is on the move with Active Steering Assist switched on. If there is no steering wheel movement over a longer period when Active Steering Assist is active, the system gives the driver a visual and audible prompt to place his/her hands on the wheel. If the driver fails to respond after repeated visual and acoustic prompts, either by moving the steering wheel, accelerating, braking or by pressing the touch control button on the steering wheel, the car is slowed down in the identified lane until it comes to a standstill. At speeds below approx. 60 km/h the following traffic is warned by means of hazard warning lamps. When the vehicle comes to a standstill, the parking brake is engaged automatically and the Mercedes-Benz emergency call system is activated. The vehicle is also unlocked, to allow first responders access to the interior. The functions are aborted as soon as the driver takes control of the vehicle again.
Active Brake Assist: Active Brake Assist with cross-traffic function is able to help the driver avoid impending collisions with vehicles ahead, stationary or crossing vehicles and with people if the driver fails to take any action to defuse the dangerous situation. This assistance takes the form of
- a distance warning from a warning lamp in the instrument cluster, if the distance from a vehicle in front is insufficient
- an additional acoustic warning if the danger of collision is identified
- braking assistance as appropriate to the given situation as soon as the driver applies the brakes
- autonomous emergency braking to avoid a collision with moving, stationary or crossing vehicles ahead if the driver fails to respond
- autonomous emergency braking also for stationary or crossing pedestrians/cyclists.
Evasive Steering Assist: Within a speed range from 20 to 70 km/h, Evasive Steering Assist can help the driver to avoid a pedestrian detected by the assistance system using the radar sensors and stereo multi-purpose camera. If the driver initiates an evasive manoeuvre by turning the steering wheel, the system provides assistance by adding precisely calculated steering torque to support the movement of the steering wheel. This torque helps the driver to avoid the pedestrian in a controlled manner and then makes it easier to straighten the vehicle up again so that it can drive past safely. While the philosophy behind Evasive Steering Assist is to provide the driver with significant assistance, the initiative to take evasive action must come from the driver. This is because if evasive action were automatic, a previously inattentive driver might be so surprised by the spontaneous movement of the steering wheel that they might react incorrectly and, for example, attempt intuitively to steer in the opposite direction.
Active Lane Keeping Assist: This system is able to warn the driver by means of pulsed vibrations at the steering wheel when the vehicle is unintentionally drifting out of its lane at speeds between 60 and 200 km/h. If the vehicle passes over a continuous line, it can pull the vehicle back into lane by applying the brakes on one side. In the case of a broken line, such intervention takes place only when there is a danger of collision with a vehicle in the next lane (including danger from oncoming traffic).
Active Blind Spot Assist: In the speed range from approx. 12 to 200 km/h, this system is able to provide the driver with a visual alert plus an audible alarm when a turn indicator is actuated, to warn of a danger of side collisions with other vehicles, including bicycles, for example. At standstill this also works when leaving the vehicle, enabling e.g. collisions with cyclists to be avoided when opening a door. At speeds above 30 km/h, the Driving Assistance package can also automatically apply one-sided braking action to help avoid a side collision at the last moment.
Traffic Sign Assist: Image recognition and information from the digital road map in the navigation system allow the permitted maximum speed and any restrictions on overtaking for the current route section and zebra crossings to be computed and shown in the instrument cluster. Additional restrictions such as speed limits in wet conditions (warning when the windscreen wipers are switched on) or speed limits for trucks only are also taken into account or ignored as appropriate in the individual case concerned. The vehicle speed is compared with the speed limit. If set to do so by the driver, a visual/visual-audible warning is given if the speed limit is exceeded. No-entry signs are also recognised and the driver is prompted to check the vehicle’s direction of travel. A warning additionally appears in the instrument cluster and on the head-up display if pedestrians are detected in the area of a zebra crossing. Traffic Sign Assist is also separately available outside the assistance package.
PRE-SAFE® PLUS: Protection against danger from the rear
PRE-SAFE® PLUS can intervene when following traffic presents a danger. To this end the radar sensors in the rear bumper monitor following traffic to detect an impending rear-end collision. If a dangerous situation is recognised, the system warns the driver of the vehicle behind by operating the hazard warning flashers at increased frequency (not in USA/Canada). It also preemptively initiates PRE-SAFE® occupant protection measures, especially the reversible belt tensioners. If the vehicle is at a standstill, PRE-SAFE® PLUS also applies the brakes firmly. This reduces the forward jolt from the impact, considerably lowering the loads acting on the occupants and the risk of whiplash injuries. Moreover, locking the brakes can prevent secondary collisions e.g. on junctions with crossing pedestrians or a vehicle ahead.
Easier parking and manoeuvring: further assistance systems on request
Active Parking Assist with PARKTRONIC assists the driver when searching for a parking space and when entering or leaving parallel or end-on parking spaces. In the case of end-on parking spaces it is active in both forward and reverse direction. It manoeuvres the vehicle into the selected parking space and out again. In the process, acceleration, braking and gear-changing is automatic if the 7G-DCT dual clutch transmission is installed. In combination with Blind Spot Assist, the system can warn the driver of cross-traffic when reversing out of end-on parking spaces, and also initiate automatic braking if necessary. PARKTRONIC gives a visual and acoustic warning of recognised obstacles with the help of six ultrasonic sensors in each bumper. These can be in front of, to the side or behind the vehicle, and are recognised at speeds up to approx. 10 km/h.
If the Parking package with 360° camera is specified, an all-round view is provided by the 360° camera with four networked close-range cameras in the radiator grille, boot lid handle and exterior mirror housings. The information is clearly presented in selectable views in the MBUX display.
The Parking package combines Active Parking Assist with a reversing camera in the boot lid. Its image is shown in diagrammatic form with superimposed guide lines in the MBUX display. The reversing camera is also available separately.
Aerodynamics: Extensive improvements by computer and wind tunnel
Good fuel consumption figures require good aerodynamic qualities. With a Cd figure from 0.25, the new A-Class betters its already very good predecessor despite increased exterior dimensions and the high model variance.
With a Cd figure from 0.25 and a frontal area (A) of 2.19 m2, the new A-Class is the aerodynamic leader in its segment. To achieve this goal, the aerodynamics engineers have performed intensive detail work during computer-based airflow simulations and optimisations in the wind tunnel and, based on the results, implemented a series of effective measures.
For the first time in the compact class, Mercedes-Benz uses a two-section AIRPANEL (optional). This louvre system behind the radiator grille opens its adjustable louvres depending on the cooling requirement. There is an additional louvre system in the air inlet below the registration plate, which further improves system performance.
The front and rear wheel spoilers have been specifically optimised to achieve low airflow losses around the wheels. In addition the wheel arches are insulated from the engine compartment (depending on engine variant) and the radiator surrounds are sealed. This ensures more precise direction of the cooling air and a more efficient cooling system.
Further detailed aerodynamic measures include:
- sealed headlamp surrounds
- new exterior mirror on the beltline
- aero lip in the bonnet’s joint to the front apron
- large roof spoiler, side spoiler, spoiler lips in the tail lights (standard) and on the rear bumper reduce air resistance and lift
- underbody panelling with large engine compartment, main floor, rear axle and diffuser panels
- improved shape of the rear exhaust silencer and heat shield (petrol engine)
- aerodynamically optimised wheels and tyres
- Wind noises have been considerably reduced in the new A-Class compared to its predecessor. This was made possible by improvements in several areas. Sources of low-frequency noise were first identified with the help of numerical simulation, and reduced in effect by design measures before detailed fine-tuning on the test benches.
Where the high-frequency wind noises are concerned, particular attention was paid to the shape of the A-pillars in conjunction with the new exterior mirrors on the beltlines. The exterior mirrors were optimised in shape and position. The result was a reduction in wind noise and air resistance. Further important improvements were achieved in the design of the seals in the windscreen surrounds and the sealing of trim elements and detachable parts.
Body and passive safety: Safety and quiet running at the highest level
A rigid and intelligently designed body provides the basis for both crash safety and pleasant acoustics. Safety is also enhanced by specifically deformable crumple zones, and quiet running by numerous other measures. Nonethelesss the weight of the bodyshell has been kept at the level of the preceding model.
The new Mercedes-Benz A-Class is also the first Mercedes-Benz model to have been developed at the new Technology Centre for Vehicle Safety (TFS). The design of the vehicle structures incorporates findings from research into real accidents. Every single bodyshell component was developed according to the loads and stresses encountered, with respect to geometry, material thickness, joining technology and material quality (increased proportion of high-strength and ultra high-strength sheet steel).
The centrepiece of the body’s safety concept is the highly rigid passenger cell. Its great rigidity when subjected to accident-induced stress e.g. in frontal, lateral or rear-end collisions and rollovers is above all due to the greater use of high-strength, ultra high-strength and press-hardened sheet steel.
The strength of the entire side wall is increased by a floor assembly with high transverse rigidity. In the front footwells this is brought about by two inner and one outer reinforcing section between the inner shell of the front side members and the central tunnel. There is a continuous seat cross-member in the rear. These are augmented by seats with high transverse rigidity featuring tubular sections in the seat frame.
The upper area of the B-pillar is extremely rigid, with hot-formed ultra high-strength steel, while the lower area is slightly less rigid with deformable, ductile steel. This gives the B-pillars very good deformation kinematics. The steel doors have specific reinforcements, and additional protection is provided by impact elements in the side seat and B-pillar claddings.
The so-called Inertia door handles are the result of in-house accident research. These even more reliably prevent a door from opening during an accident, as the door is locked in place at the handle when subjected to impact-induced forces.
Special measures for the structural safety of the vehicle’s front section include the following:
- the robust firewall cross-member of hot-formed, press-hardened steel between the two A-pillars
- several parallel load paths for improved load distribution in a partial frontal collision (offset crash)
- side members at the upper impact level connected to the A-pillars
- effective load distribution from the front side members by means of specially reinforced A-pillars
- a middle impact level with side members having specific crash kinematics
- multi-layered floor structures for optimum energy absorption
- an additional pedal floor cross-member to protect the footwell
- continuous floor side members to improve energy transfer into the underbody structure, with a larger cross-section and material thickness than in the previous model
- compatibility with other vehicles in the design of the front structure in the event of a frontal collision (protection of other road users).
- The more compact drive units also play an important role. During a frontal collision, and acting together with the body structure, they allow more homogeneous deceleration and help to ensure the occupant protection for which Mercedes-Benz is well-known. Depending on impact severity, the engine and transmission are specifically displaced and disengaged from the new integral carrier.
Vehicles with a tailgate require a particularly well-conceived rear body structure to compensate for the large aperture. For many years, e.g. in the E-Class Estate models, the structural concept of two peripheral sections has proved successful for Mercedes-Benz: the so-called C-ring at the level of the C-pillar and the D-ring around the tailgate aperture. Thanks to the geometry of the D-ring, it was possible to position the lower section of the C-ring completely below the rear floor while retaining the excellent rigidity of the previous model. This enlarged the load capacity and made a level load area possible.
Restraint systems: partnership with the safety bodyshell
The most important restraint system is the seat belt. The driver and front passenger each have a three-point seat belt with belt force limiter and belt tensioner. In conjunction with the PRE-SAFE® system (optional equipment, the front seats are equipped with reversible belt reel tensioners. Both of the outer rear seats are fitted with a seat belt with reel tensioner and belt force limiter. These excel with a relatively low level of force for small and lightweight occupants. The centre belt is a standard three-point belt.
The new A-Class is equipped with driver and front passenger airbags, a driver’s kneebag and windowbags as standard. Unlike in many competing models, the windowbag also covers the A-pillar for more complete passenger protection. Thorax-pelvis sidebags are likewise standard in the front, and available as optional equipment for the rear.
Child safety: automatic deactivation of the front passenger airbag
A pressure sensor in the front passenger’s seat cushion can detect whether the seat is unoccupied or whether an infant or other child seat has been placed on the front passenger seat, and in the latter case deactivate the front passenger airbag automatically. Contrary to other systems that require the airbag to be deactivated with a key, this system reduces the risk of incorrect operation. As no special transponder is required, the system can be used for all conventional, rear-facing child restraint systems. The system is standard or optional equipment depending on the market or region.
i-Size child seat attachments are used for i-Size child seats. This internationally standardised attachment system, the successor to Isofix, is provided for the outer rear seats as standard. It improves protection with a fixed connection between the child seat and the vehicle.
Pedestrian protection: active bonnet
Reducing the severity of an impact is particularly important in the case of a collision with vulnerable road users such as pedestrians, as these have no “crumple zone” of their own. This is where the active safety systems of Intelligent Drive come into their own. If an impact is unavoidable, the further developed measures to mitigate the consequences of accidents involving pedestrians can help.
The active bonnet is an important factor in this. The technical basis is a comprehensive sensor system in conjunction with intelligent algorithms in the airbag control unit, which decides when to trigger. After activation of the pyrotechnical actuators, the bonnet is raised on its hinge by a significant 80 mm or so within fractions of a second. This creates additional space between the bonnet and the components in the engine compartment. The protective effect is increased by a comparatively flexible cross-member below the windscreen. This is designed in the form of a shackle, enabling it to give way better in the event of a head impact.
Noise and vibrations: there is strength in serenity
Quiet, vibration-free driving characteristics are a major factor in the grown-up, premium driving impression made by the new A-C lass. Alongside effective insulation of the suspension from the vehicle body see section on Suspension and aeroacoustic measures, the bodyshell itself plays a decisive role.
During the development of the A-Class, particular attention was given to high overall structural rigidity and the connecting points between the body, suspension and powertrain. Significant increases in introduction rigidities were especially achieved at the suspension connecting points that are so important to road roar, and the interior noise level was considerably reduced.
Following examination of the previous model, the guide bearing of the front axle and the rear connection of the subframe were identified as major introduction points. The introductory rigidity at the front axle guide bearing was significantly increased with a compact, rigid integral carrier.
The subframe of the multi-link rear axle is elastically isolated by rubber bushings. The front subframe connection is integrated into the C-ring structure of the bodyshell, and therefore has the rigidity to isolate it. A cross-member is integrated into the multifunction recess to increase the introductory rigidity of the rear subframe connection. This not only gives transverse support to the subframe carrier, but also stiffens the membrane surface of the recess. This reduces sound radiation as a good basis for efficient noise insulation.
To reduce the noise impact to the passenger compartment, the firewall is a high-quality injection-moulded component. In contrast to deep-drawn components, this has the advantage that constant wall thicknesses are possible: large changes in contours do not thin out the material – a classic acoustic weak point. In addition a modular major assembly compartment partition made of plastic is used by Mercedes-Benz for the first time for a platform with transversely installed engines. This makes models with the top engine variants particularly quiet-running.
The comprehensive noise insulation concept of the new Mercedes-Benz A-Class includes components such as the air and coolant management systems or trim parts in the interior being configured so as to improve noise insulation as well. Sound insulation measures also include the specific use of absorbers e.g. in the area of the C-pillars, in body cavities and with spring-mass systems on the wheel arches. The tool used for all sound insulation measures was statistical energy analysis -SEA-. This makes it possible to assess the effect of sound insulation concepts at a very early stage with the help of computer models.
Drive system: New engines, new transmissions
All the new A-Class models are powered by new, efficient engines: Two new four-cylinder petrol engines are available at market launch. Innovations in the M 282 with a displacement of 1.4 litres and up to 120 kW include cylinder shutoff *in conjunction with the 7G-DCT transmission* and the delta shape of the cylinder head. The second new petrol engine is the M 260 with a displacement of 2.0 litres, 165 kW and 350 Nm. New features include CAMTRONIC for the intake camshaft. Both petrol engine series have low-friction cylinder walls and a particulate filter as standard. Also new is the four-cylinder diesel *OM 608* with a displacement of 1.5 litres, up to 85 kW and up to 260 Nm. Its highlights are a near-engine mounted emission control system with AdBlue® technology, a turbocharger with optimised response time and water intercooling. A new 7G-DCT dual clutch transmission is also being introduced. Further new engines will follow. The fuel tank has a capacity of 43 litres as standard, with a 51-litre tank optionally available.
The following three engine variants will be available on the launch of the A-Class, or shortly afterwards:
- A 200 – 120 kW/163 hp, 250 Nm; with 7G-DCT dual clutch transmission combined fuel consumption 5.1 l/100 km, combined CO2 emissions 120 g/km or six-speed manual transmission – combined fuel consumption 5.6 l/100 km, combined CO2 emissions 133 g/km
- A 250 with 7G-DCT dual clutch transmission – 165 kW/224 hp, 350 Nm; combined fuel consumption 6.0 l/100 km, combined CO2 emissions 141 g/km
- A 180 d with 7G-DCT dual clutch transmission – 85 kW/116 hp, 260 Nm; combined fuel consumption 4.1 l/100 km, combined CO2 emissions 108 g/km
- The new M 282 petrol engine: four-cylinder with cylinder shutoff
The new entry-level engine in the A 200 is the M 282 with a displacement of 1.33 litres. Compared to the previous 1.6-litre engine, the output of this all-aluminium engine has increased by up to eleven percent and the output per litre by no less than 25 percent. This engine excels with very compact dimensions, low weight and high static and dynamic rigidity. The turbocharger features an electronically controlled wastegate: thanks to flexible charge pressure control, it is also possible to set an optimum charge pressure under partial-load conditions.
This is the first four-cylinder Mercedes-Benz engine to feature cylinder shutoff *initially in conjunction with the 7G-DCT transmission*. In the partial load range between 1250 and 3800 rpm, and depending on the power requirement, the intake and exhaust valves of the second and third cylinder are closed by valve clearance adjustment. The remaining two cylinders therefore operate under higher loads, and more efficiently. To minimise friction, the cylinder walls are coated using the patented NANOSLIDE® process. The piston skirts are given an Eco-Tough coating, a special graphite coating for optimised friction and high wear resistance.
Another special technical feature is the delta cylinder head, so called because of its shape. It is slightly higher when installed, but much narrower and lighter than conventional cylinder heads. Further advantages include the semi-integrated intake and exhaust manifolds, which allow compact construction. Daimler holds a patent for the compact arrangement of the high-pressure injection pump with a maximum of 250 bar. The multi-hole injection nozzles are centrally located in the combustion chamber, and injection occurs without the valves being subjected to the jet of fuel.
This new, high-compression four-cylinder engine has a particulate filter as standard. Particular effort was also devoted to noise emissions. The intake air duct features a Helmholtz resonator, the catalytic converter has insulating seals and the cover also has a noise-reducing role.
The new engine will initially be available with the 7G-DCT dual clutch transmission, and later also with a six-speed manual transmission and 4MATIC all-wheel drive.
The M 282 was developed by Mercedes-Benz in cooperation with Renault. It is produced at the Kölleda plant in Thuringia, Germany and in future it will also be produced in Beijing, China. Renault supplies the components of the long block engine.
The new M 260 petrol engine: premiere of CONICSHAPE®
The M 260 four-cylinder engine of the A 250 is essentially a further development of the previous M 270, with an output increase of over 6 percent compared to its predecessor. Its engine block of diecast aluminium with cast iron cylinder liners conceals a world premiere in large-scale production: CONICSHAPE®, also known in-house as “trumpet-honing”. To further minimise piston friction and lower fuel consumption, the cylinder bore is widened at the lower end of the cylinder liners. The resulting, conical shape resembles the mouth of a trumpet. An innovative low-friction oil and optimised piston rings also reduce friction losses. To take account of the higher specific output, the pistons themselves feature cooling ducts. This also ensures more efficient combustion. The balance shafts for smooth engine-running are located in the lower section of the crankcase.
Also new in the aluminium four-valve cylinder head of the two-litre engine is CAMTRONIC, a variable valve timing system that allows two-stage adjustment of the valve lift on the intake side of the valve assembly. In the partial-load range, this variable valve lift adjustment allows less air to be fed to the combustion chamber with a smaller valve lift, which leads to lower gas cycle losses. In higher load ranges the system switches to the higher valve lift to achieve the engine’s full power delivery.
Multiple fuel injection ensures optimum combustion despite the smaller valve lift. This compensates the reduced turbulence of the fuel/air mixture in the combustion chamber in the area of the spark plug. The four-cylinder has direct injection with latest-generation piezo injection valves. The position of the injectors has been optimised to achieve low cylinder wall coverage and therefore lower untreated emissions, especially particulate emissions. A particulate filter is included as standard. Thanks to optimised injection with partial valve lift, the engine runs even more quietly in wide operating ranges. A low level of exhaust emissions has been achieved by further development of the well-proven BlueDIRECT combustion system in conjunction with the standard petrol particulate filter.
The single-pipe turbocharger features an electronically controlled wastegate valve. The previously vacuum-operated actuator has been replaced by a precision electrical actuator, which reports its position and has a higher actuating speed, so that charge pressure control and diagnosis are significantly improved. This allows charging to be more precisely controlled.
The oil circuit is supplied with engine oil on a demand basis. Sensors monitor the oil pressure so that the supply volume can be adjusted. The cooling circuit has an electronically controlled thermostat which allows the engine temperature to be optimally set to suit needs.
To make engine operation more comfortable, a new centrifugal damper has been introduced into the powertrain as an addition to the balance shafts. This improves the engines NVH characteristics and allows comfortable driving possible at lower rpm. The exhaust system with flap control has the same purpose.
The engine is configured for front-wheel drive and 4MATIC all-wheel drive, and combined with the 7G-DCT dual clutch transmission. The M 260 engine is produced by the Kölleda plant.
The new OM 608 diesel engine: quieter and cleaner
The entry-level OM 608 diesel engine in the A 180 d is a new development based on the OM 607. It is more powerful *85 kW, 5 kW more*, has further reduced emissions, complies with EU 6d temp including the new requirements relating to Real Driving Emissions – RDE, and has optimised noise characteristics.
New technological components include the improved turbocharger with variable turbine geometry integrated into the exhaust manifold. An electric actuator now adjusts the turbine geometry Together this makes for a more immediate charging response. The intake air is now cooled by an engine-mounted water intercooler.
The installed height of the new aluminium cylinder head has been reduced, and the moving masses of the valve assembly reduced. The intake manifold is now integrated into the cylinder head cover. The pressure of the common-rail injection system has been increased to 2000 bar *previously: 1600 bar*. The electro-magnetically controlled injectors have eight injection holes. This allows precise combustion control by up to six injections per working cycle. Dual pre-injection is used to optimise combustion noise in wide operating ranges, and the injectors are sealed in their shafts.
The cast-iron engine block has been made lighter, while increasing its rigidity. Weight-optimised steel pistons are used as before. A demand-controlled oil pump is used, with a pressure regulating valve adjusting the oil pressure on the basis of need and temperature-dependent characteristics maps.
For sound insulation, the sump has a polyurethane foam cover, the engine cover an interior foam lining and the design cover an interior PET lining.
For low emissions, the OM 608 is equipped with high and low-pressure exhaust gas recirculation. The compact exhaust aftertreatment system is near-engine mounted. Alongside the oxidation catalytic converter and the particulate filter, SCR catalytic converters with AdBlue® metering are used for the first time in this engine class. The particulate filter also has an SCR coating. A large AdBlue® tank with a capacity of 23.8 litres ensures long refilling intervals, and has its own, externally accessible filler neck next to the diesel filler neck.
At market launch the engine is available with a new 7G-DCT dual clutch transmission. The OM 608 was developed as part of a strategic cooperation with Renault. The Mercedes-Benz specific technology components include:
- engine mounting
- special two-mass flywheel
- dual-clutch transmission
- alternator and air conditioner compressor
- engine control unit with specific software
- ECO start/stop function
- The 7G-DCT transmissions: comfortable and economical
In the new A-Class, Mercedes-Benz uses two different 7G-DCT dual clutch transmissions with a wet clutch: The previous transmission has been developed further for the more powerful engines – e.g. A 250. It has been improved in shift performance and reaction time by an optimised friction system and pistons with a lower hysteresis. To transfer the driver’s shift commands even more directly, communication between the engine and transmission has been revised. Control of the available drive programs ECO, Comfort, Sport and Individual has also been adapted.
The A 200 and A 180 have a newly developed 7G-DCT dual clutch transmission. For a low dry weight of 67 kg, the actuators exhibit high mechanical and electrical efficiency. The gears are shifted electro-mechanically, the wet clutches are operated electrohydraulically. The software-controlled clutch allows different shift characteristics – from sporty to particularly comfortable – with the driver able to choose between ECO, Comfort, Sport and Individual. As further functions it allows extended coasting and ECO start/stop. This transmission was developed together with GETRAG, who is also the supplier.
Suspension: Agile and comfortable
There is a choice of suspension systems for the Mercedes-Benz A-Class, depending on engine variant and driver preference. 16-inch wheels are standard equipment. DYNAMIC SELECT is standard equipment, and at the touch of a button also provides an individual driving experience in conjunction with active damping control *optional.
Like all its predecessors, the new A-Class has a McPherson front suspension. Wheel control is taken care of by one transverse control arm below the wheel centre, the McPherson strut and one tie rod. The transverse control arm in the new A-Class is a forged aluminium component. This reduces both weight and unsprung masses. The steering knuckles are made of cast aluminium.
The wheel-locating McPherson struts feature transverse force-optimised coil springs and twin-tube gas-pressure shock absorbers with auxiliary springs. The support bushing is a three-way design, with the forces applied by the damper, spring and auxiliary spring isolated from each other. Here too, attention was paid to low weight with a hollow piston rod, aluminium head bearing and a perforated spring plate. The tubular stabiliser is connected to the suspension struts by a newly developed, weight and friction optimised torsion bar linkage of hybrid polyamide construction.
When defining the axle geometry, particular attention was paid to keeping torque steer to a minimum and eliminating jolts as far as possible. The form and arrangement of the rubber bushings determines the great agility of the vehicle, also allowing a high level of ride comfort and driving safety.
Steering: also supports automated driving
The gearing of the electro-mechanical rack-and-pinion steering is located behind the wheel centre, and servo assistance is speed-sensitive as standard. The steering assistance function *in conjunction with the Driving Assistance package* is a new feature. The driver’s steering movements to stabilise the vehicle are assisted by additional steering torque generated by the electric servo unit.
- countersteering in case of oversteer
- steering corrections when braking on varying road surfaces *μ-split braking*
- reducing the steering effects of front-wheel drive
- compensation for crosswinds and road camber.
- In combination with Active Distance Assist DISTRONIC, transverse control takes place to add active lane-keeping to the intelligent cruise control.
Rear axle: four control arms, high proportion of aluminium
The more powerful A-Class versions such as the A 250 and all 4MATIC models have a sophisticated four-link rear suspension. The three transverse arms and one trailing arm at each rear wheel are configured for maximum driving stability, comfort and longitudinal/lateral dynamics. The rear axle is mounted on a subframe isolated from the bodyshell by rubber bushings so that fewer vibrations are transferred from the suspension to the body.
The wheel carrier and spring control arm are made of aluminium – low unsprung masses allow a particularly sensitive “feel” for the road surface. All in all, the proportion of aluminium in the suspension components is one of the highest in any suspension system in this vehicle class. Newly developed shift rails made of polyamide connect the torsion bar stabiliser with the rear axle.
The entry-level A 200 and A 180 d models have a torsion beam rear suspension. Its U-section rotates in a targeted manner in one-sided compression and rebound, and acts as a stabiliser bar. The torsion-beam rear axle is secured to the body with two bearings and uses the same attachment points to the body-in-white as the multi-link axle’s trailing arm.
Single-tube shock absorbers and separate coil springs are used for both the four-link and the torsion-beam rear axle. Here too, effective noise insulation of the coil spring between the body and rear axle is achieved with two elastomer insulators. The connection between the shock absorber and the body is via an aluminium bearing, which by way of its soft gimbal-type mount contributes to a reduction in friction in the damper and therefore to an improvement in response.
Three suspension variants: choice of setups
As standard the new Mercedes-Benz A-Class is equipped with a comfort suspension with steel springs and DYNAMIC SELECT. The comfort suspension lowered by 15 millimetres has specially configured springs and dampers for more sporty characteristics.
The suspension with active damping control enables the driver to choose the preferred damping characteristics. A valve in each of the four shock absorbers is electronically actuated to control the oil flow. The damping characteristics are changed by regulation of the oil flow.
Several different sensors constantly monitor the suspension status, driving situation and driving style of the driver, and adjust the damping at each wheel. Information is also added by the engine, transmission, braking system, steering and driving assistance systems. The damping is specifically stiffened during acceleration, braking or steering manoeuvres to reduce pitching and body roll, and to improve wheel loads and tyre adhesion.
Brakes: ADAPTIVE BRAKE as standard
The new A-Class has a hydraulic dual-circuit braking system in X-configuration with the brake control function ADAPTIVE BRAKE as standard. The dimensions take vehicle-specific circumstances such as axle load distribution, weight and performance into account. The electric parking brake is standard equipment. The rear axle features a combined floating brake calliper with an electric parking brake function.
ADAPTIVE BRAKE puts technology from the top-of-the-line model Mercedes-Benz models into the A-Class. Thanks to electronic control, the hydraulic dual-circuit braking system allows assistance functions that improve safety and comfort. This includes priming of the braking system in critical situations: if the driver’s foot moves abruptly from the accelerator to the brake pedal before an emergency stop, the braking system increases the pressure in the brake lines and brings the pads into contact with the brake discs so that maximum braking power is available as soon as the driver hits the brake pedal. This priming of the brakes allows the system to assist the standard Brake Assist.
ADAPTIVE BRAKE also brings safety benefits in wet conditions. The system briefly applies the brakes at regular intervals to wipe the film of water from the brake discs, ensuring that the brakes are able to perform at their peak. This automatic brake drying function is always activated when the windscreen wiper of the Mercedes-Benz A-Class has been switched on for a certain time, and the finely metered braking impulses go unnoticed by the driver.
After braking to a standstill, briefly pressing the brake pedal a little further is all that is required to activate the HOLD function. The car is then held by the brakes, even if the driver’s foot is taken off the brake pedal. In this way ADAPTIVE BRAKE prevents unintentional moving-off at traffic lights or in stop-and-go traffic, or rolling backwards on uphill gradients. The HOLD function is deactivated automatically when the car moves off.
The range of wheels and tyres begins at 16 inches. It comprises steel wheels in size 16 and 17 inches and light-alloy wheels in size 16 to 19 inches. The overall outer diameter of the wheels/tyres is 660 mm rather than the previous 645 mm.