Delay between between European and Australian launches
Steering feel?
Rear seat headroom?
Overview
To be released in Australia in late 2019, the Mercedes-AMG W177 A-Class is a five-door hot hatch. Manufactured in Rastatt, Germany, the all-wheel drive Mercedes-AMG W177 A 35 and A 45 S are powered by 2.0-litre turbocharged four-cylinder petrol engines that are mated to seven- and eight-speed double clutch transmissions, respectively.
Mercedes-AMG W177 A 35: M260 engine and AMG Speedshift DCT
The 1991 cc M260 engine for the Mercedes-AMG W177 A 35 features an aluminium crankcase, ‘ConicShape’ cylinder honing to reduce internal friction, an aluminium-silicon alloy cylinder head with chain-driven double overhead camshafts, four valves per cylinder actuated via roller cam followers, variable intake valve lift (‘Camtronic’), variable intake and exhaust valve timing, direct injection via piezo injectors, a twin-scroll turbocharger and multi-spark ignition. To eliminate fuel consumption when the vehicle is stationary in traffic, the M260 engine for the Mercedes-AMG W177 A 35 has an ECO start/stop function, though this is disabled in Sport and Sport+ drive modes.
For the Mercedes-AMG W177 A 35, the seven-speed double clutch transmission (DCT) has:
A Race-Start function;
A Temporary ‘M’ (manual) mode that can be activated by operating the steering wheel shift paddles in any driving mode; and,
For the Sport+ drive mode, double-declutching during downshifts and partial cylinder cut-off via a brief and precisely defined retardation of ignition and injection at full load.
The Mercedes-AMG W177 A 35 can accelerate from rest to 100 km/h in 4.7 seconds. Over the combined NEDC test cycle, fuel consumption is 7.4 litres per 100 km.
Mercedes-AMG W177 A 45 S: M139 engine and AMG Speedshift DCT
Assembled by hand at the Mercedes-AMG engine factory in Affalterbach, the 1991 cc M139 engine for the Mercedes-AMG W177 A 45 S has an all-aluminium crankcase that is chill-cast, i.e. the molten aluminium is poured into a metallic mould and rapid cooling of the water-cooled mould achieves solidification of the melt for a dense, fine-grained structure. The crankcase also has closed-deck construction – for maximum rigidity – whereby the areas around the top of the cylinders are mostly solid and the cover plate is only penetrated by smaller ducts for the coolant and engine oil.
Unlike the M260 engine for the A 35, the M139 engine for the A 45 S is rotated around its vertical axis by 180 degrees so that the turbocharger and exhaust manifold are positioned at the rear (on the side of the firewall when viewed from behind). According to Mercedes, this configuration provides the flattest and most aerodynamic design, and improved air ducting with shorter distances and fewer diversions.
Other features of the M139 engine includes its forged steel crankshaft, forged aluminium pistons and ‘Nanoslide’ iron-carbon alloy cylinder bore coating which is applied using twin-wire arc spraying (TWAS). According to Mercedes, the ‘Nanoslide’ lining is twice as hard as conventional grey cast-iron liners. The M139 engine has four valves per cylinder that are actuated by roller cam followers, with variable intake and exhaust camshaft timing. For the exhaust valves, each valve has two cams of different geometries (‘Camtronic’) – this enables the exhaust valves to be opened for short or long periods.
The M139 engine has a twin scroll turbocharger with the following characteristics:
roller bearings to reduce mechanical friction for the shafts of the compressor and turbine; maximum speed of 169,000 rpm;
maximum charge pressure of 2.1 bar;
an overboost function under acceleration;
an electronically controlled wastegate; and,
air, oil and water cooling. For air cooling, air is directed to the charger from the radiator grille, via the engine cover and ducts beneath the bonnet.
Air is supplied to the turbocharger via a ‘two-stage, indirect intercooler’ whereby one condenser is located in the wheel arch, and a second one is positioned in the first row of the central cooling module.
The M139 engine has two-stage fuel injection –
First stage: direct injection via piezo injectors at pressures up to 200 bar; and,
Second stage: additional intake manifold injection via solenoid valves at an operating pressure of 6.7 bar.
According to Mercedes, manifold injection was ‘needed to achieve the engine’s high specific output’.
To reduce fuel consumption, the M139 engine has an ‘ECO start/stop’ function with fast restarting, gliding function (i.e. shuts down the engine and decouples the engine from the drivetrain), an electrically driven water pump for cooling of the crankcase and an on-demand alternator. To reduce emissions, the M139 engine has a petrol particulate filter.
Producing peak outputs of 310 kW at 6750 rpm (maximum engine speed is 7200 rpm) and 500 Nm at 5000-5250 rpm, the M139 is the most powerful turbocharged four cylinder engine in series production. Furthermore, the Mercedes-AMG A 45 S can accelerate from rest to 100 km/h in 3.9 seconds.
The ‘4MATIC’ all-wheel drive system for the Mercedes-AMG W177 A 35 and A 45 S includes:
A power take-off unit to the rear axle that is integrated into the dual clutch transmission; and,
A multi-plate clutch that is integrated into the rear axle differential and electro-mechanically controlled (previously electro-hydraulically actuated).
In normal conditions, the engine’s torque is directed to the front wheels for maximum fuel efficiency. Based on driving speed, lateral and longitudinal acceleration, steering angle, difference in rotational speed between individual wheels, gear selected and accelerator position, however, the electric motor can exert an axial force on the clutch pack – via a crown wheel and a ball ramp – to close the clutch plates so that 50 per cent of the engine’s torque is directed to the rear wheels (i.e. a 50:50 front:rear torque distribution). The advantages of this control system are:
Non- rpm-dependent operation across the entire actuation range;
Pilot control of the clutch while stationary; and,
Higher efficiency due to the ball ramp concept.
As part of the electronic stability control system, slight braking pressure would be applied to the inside rear wheel during ‘dynamic cornering’ to generate yaw about the vertical axis and reduce understeer. For the A 35, the rear axle differential compensates the different paths/rotational speeds of the rear wheels. For the 4MATIC+ system in the A 45 S, however, the rear axle differential has two electronically controlled multi-disc clutches, each of which is connected to a rear axle drive shaft, so that drive can be variably distributed between the rear wheels (‘AMG Torque Control’).
Body and dimensions
The Mercedes-AMG W177 A-Class is underpinned by Mercedes-Benz’s MFA2 compact car platform which is shared with the Mercedes-Benz W177 A-Class . Compared to the Mercedes-AMG W176 A 45 , the Mercedes-AMG W177 A 35 is 103 mm shorter (at 4436 mm), 17 mm wider (1797 mm), 12 mm lower (1405 mm) and has a 30 mm longer wheelbase (2729 mm); kerb weight is 1555 kg including a 75 kg driver. Relative to the W177 A 35, the W177 A 45 S is 9 mm longer (4445 mm), 53 mm wider (1850 mm) and 2 mm taller (1407 mm); kerb weight is 1650 kg including a 75 kg driver.
Compared to the Mercedes-Benz W177 A-Class, changes for the Mercedes-AMG W177 A 35 include:
A ‘shear panel’ (a bolted aluminium plate under the engine to increase the torsional stiffness of the front section); and,
Two additional diagonal braces at the front of the underbody to reduce torsion and increase stiffness.
Beyond this, the bodyshell of the W177 A 45 S is reinforced by:
A strut tower brace between the front suspension struts; and,
Additional pistol-shaped reinforcing plates to connect the side members to the A-pillars to minimise movements of the front section.
Suspension
The Mercedes-AMG W177 A 35 and A 45 S have MacPherson strut front suspension with a single aluminium wishbone below each wheel centre, one spring strut and one tie rod. According to Mercedes, the ‘special axle geometry’ reduces the influence of the drive on the steering. Furthermore, the AMG-specific front steering knuckle has a radially bolted brake calliper. At the rear, the four-link rear axle (three transverse arms and a trailing arm) is connected rigidly to the body via a sub-frame.
As standard, the Mercedes-AMG W177 A 45 S has frequency-selective shock absorbers.
As an extra-cost option, however, the Mercedes-AMG W177 A 35 and A 45 S can be specified with ‘AMG Ride Control’, i.e. adaptive damping whereby a valve in each of the four shock absorbers is electronically actuated to control oil flow and, therefore, damping characteristics. The Adaptive Damping System also enables the driver to select from three different suspension control modes. The system operates fully automatically, adapting the damping forces for each wheel according to the driving situation and road conditions.
Steering
The Mercedes-AMG W177 A 35 and A 45 S have rack-and-pinion steering with electric power assistance and a variable steering ratio. According to Mercedes, the rigid mounting in the integral carrier better connects the steering to the body for greater steering precision.
Safety equipment
Standard safety equipment for the Mercedes-AMG W177 A 35 and A 45 S includes dual front airbags, a driver’s knee airbag, front seat thorax-pelvis side airbags, full-length curtain airbags, ABS, electronic brake force distribution, brake assist, electronic stability control, traction control and front seatbelts with pre-tensioners and load limiters.
The Mercedes-AMG W177 A 35 and A 45 S are equipped with camera and radar systems that can perceive up to 500 metres ahead of the vehicle. Fitted as standard, Active Brake Assist with cross-traffic function can mitigate the consequences of collisions with vehicles or pedestrians in front of the vehicle. If a collision risk is detected, the system initially issues a visual warning. If there is a serious risk of collision, the driver receives an additional, audible warning and the required brake pressure to prevent a collision is calculated (if possible) so that it can be applied when the driver depresses the brake pedal. If the driver fails to respond, however, Active Brake Assist initiates autonomous emergency braking to mitigate or prevent the collision.
Other active safety technologies for the Mercedes-AMG W177 A 35 and A 45 S include:
Active Emergency Stop Assist: if it is detected that the driver is no longer actively driving the vehicle while it is moving, Active Emergency Stop Assist brings the vehicle to rest within its lane. If there is no steering wheel movement over a longer period when Active Steering Assist (see below)) is active, the system issues visual and audible prompts for the driver to place their hands on the steering wheel. If the driver fails to respond, vehicle speed is reduced until it is stationary. At speeds below 60 km/h, following traffic is warned by the hazard warning lamps;
Active Distance Assist Distronic with Active Steering Assist: operating at speeds up to 210 km/h, the system can maintain a pre-set distance to the vehicle ahead. A stop-and-go function also enables the vehicle to be braked until stationary, remain stationary for up to 30 seconds and then accelerate when the traffic ahead starts moving. Active Distance Assist Distronic also combines navigation data with camera/radar inputs to conveniently adjust speed when approaching bends, junctions or roundabouts. Active Steering Assist helps the driver in keeping the vehicle in the centre of its lane by applying steering wheel torque. Active Steering Assist uses the lane markings for orientation at speeds up to 210 km/h and, at speeds up to 130 km/h, also uses the position of vehicles ahead;
Evasive Steering Assist: operating at speeds from 20-70 km/h, Evasive Steering Assist can help the driver avoid a pedestrian that is detected by the radar sensors and stereo camera. If the driver initiates an evasive manoeuvre by turning the steering wheel, the system provides ‘precisely calculated steering torque to support the movement of the steering wheel’ to avoid the pedestrian and then straighten the vehicle;
Active Lane Change Assist: operating at speeds from 80 km/h to 180 km/h, Active Lane Change Assist can perform lane changes – within 10 seconds – in response to the driver nudging the indicator stalk;
Active Lane Keeping Assist: operating at speeds from 60 km/h to 200 km/h, Active Lane Keeping Assist warns the driver if the vehicle is unintentionally drifting out of its lane via pulsed vibrations through the steering wheel. If the vehicle passes over a continuous line, the system can pull the vehicle back into its lane by applying the brakes on one side of the vehicle. In the case of a broken line, such intervention takes place only when there is a collision risk with a vehicle in the adjacent lane (including oncoming traffic);
Active Blind Spot Assist: at speeds from 12 km/h to 200 km/h, the system can provide a visual alert and audible alarm if there is a risk of a side collision when the turn indicator is actuated. As part of the Driving Assistance Package, the brakes on one side of the vehicle can be applied when travelling at speeds above 30 km/h to avoid a side collision. Furthermore, Active Blind Spot Assist can issue a visual warning in the door mirror when the vehicle is stationary and up to three minutes after the ignition has been turned off to warn of an approaching vehicle or bicycle (providing it is exceeding 2 m/s). If the driver uses the door handle at this moment, an additional acoustic warning is issued;
Pre-Safe Plus: uses the rear radar sensors to detect if a rear-end collision is imminent and, if so, flashes the rear hazard lights and prepares occupant protection measures such as the seatbelt tensioners. If the vehicle is stationary and the risk of a collision persists, the system can apply the brakes of the vehicle to reduce the risk of injuries by reducing the forward jolt caused by an impact from the rear;
Attention Assist: monitors driver behaviour for signs of fatigue and, if detected, issues visual and audible warnings; and,
Traffic Sign Assist: uses navigation data and image recognition to display – in the instrument cluster – the maximum permitted speed, restrictions on overtaking and pedestrian warnings near ‘zebra’ crossings. Traffic Sign Assist also has an extended wrong-way warning, while the detection of stop signs has been combined with the ECO start/stop function so that the engine remains on. Active Speed Limit Assist is a sub-function of Traffic Sign Assist that uses the forward-facing camera to recognise sign gantries and road works signs to set the vehicle’s maximum speed.
The Mercedes-AMG W177 A 35 and A 45 S have an ‘active bonnet’ which, in the event of a pedestrian collision, deploys pyrotechnical actuators to raise the height of the bonnet by around 80 mm to create additional clearance between the bonnet and components in the engine bay to reduce the risk of pedestrian injury.
Euro NCAP testing: Mercedes-Benz W177 A-Class
In Euro NCAP testing , the Mercedes-Benz W177 A-Class received a five star safety rating which included a 96 per cent adult occupant protection rating and a 91 per cent child occupant protection rating. In the frontal offset test, protection for the driver’s head, thighs and feet were rated as good, though chest and lower leg protection was rated as adequate (i.e. a slight risk of serious injury). Maximum points were awarded in the side impact test; in the more severe pole test, however, chest protection for the driver was rated as adequate.
Brakes
The Mercedes-AMG W177 A 35 has 350 mm by 34 mm front brake discs with four-piston monoblock fixed callipers, while the A 45 S has 360 mm by 36 mm front brake discs with six-piston fixed callipers. Both models, however, have 330 mm by 22 mm rear discs with single piston sliding callipers. Furthermore, the front and rear discs are internally ventilated and perforated to better dissipate heat.
Features: Mercedes-AMG W177 A 35 and A 45 S
The Mercedes-AMG W177 A 35 and A 45 S feature the ‘Mercedes-Benz User Experience’ (MBUX) multimedia system which includes two 10.25-inch displays – for a fully digital instrument display and a central touchscreen – which share glass cover and form a ‘Widescreen Cockpit’
Inside, the Mercedes-AMG W177 A 35 has:
Seat covers in ‘Artico’ synthetic leather and ‘Dinamica’ micro-fibre;
A steering wheel rim with a flattened lower section, perforated leather in the grip area, red contrasting top-stitching and ‘Touch Control’ buttons which can be used to select the displays of the instrument cluster and the multimedia system through horizontal and vertical swiping gestures; and,
Galvanised steering wheel gearshift paddles. As an option, the steering wheel can be equipped with a round controller that has an integrated display beneath the right-hand steering-wheel spoke, and two vertically positioned colour display buttons with switches beneath the left-hand steering-wheel spoke.
Further information regarding the Mercedes-AMG W177 A 35 and A 45 S will be available closer to launch.
