The FINANCIAL — Mercedes-AMG is accepting the challenges of motoring of the future: the SLS AMG E-CELL is evidence of the state-of-the-art development of an exciting super sports car featuring a zero-emission high-tech drive.
Boasting a power output of 392 kW and 880 Nm of torque, the technology vehicle from AMG is able to offer exceptional performance. The gullwing with electric drive is part of the company strategy entitled "AMG Performance 2015" which aims to continually reduce fuel consumption and emissions.
"With the SLS AMG E-CELL, Mercedes-AMG is providing a glimpse of its latest development project – a powerful and locally emission-free super sports car. Finished in fluorescent "AMG lumilectric magno" paint, the gullwing offers the prospect of a possible small series production run and at the same time reflects the innovative strength and development competence of the AMG performance brand," Daimler informs.
"We take social responsibility very seriously and with the SLS AMG E-CELL we are demonstrating a further milestone in our "AMG Performance 2015" strategy. It is our goal to continually reduce the fuel consumption and emissions of new models in the coming years, while at the same time enhancing the core brand value of performance", explains Ola Källenius, chairman of the board (from 1 July 2010) of Mercedes-AMG GmbH. With the SLS AMG E-CELL, the performance brand of Mercedes-Benz is launching a totally innovative drive solution for super sports cars and as such is among the pioneers in this market segment.
The ground-breaking drive system of the technology vehicle boasts some outstanding features: powerful traction is provided by four synchronous electric motors with a combined peak output of 392 kW and a maximum torque of 880 Nm. The four compact electric motors each achieve a maximum rpm of 12,000/rpm and are positioned near to the wheels. As a result, compared with wheel-hub motors the unsprung masses are substantially reduced. One transmission per axle transmits the power.
Acceleration from zero to 100 km/h in 4 seconds
When it comes to dynamics, the electrically-powered SLS AMG makes a statement: the gullwing model accelerates from zero to 100 km/h in 4 seconds – which almost puts it on the same high level as the SLS AMG with 6.3-litre V8 engine developing 420 kW (571 hp), which can accelerate to 100 km/h in 3.8 seconds.
Further exciting touches are provided courtesy of the agile accelerator response and the straight-line performance: unlike the combustion engine, torque build-up with an electric motor is instantaneous – maximum torque is available virtually from a standstill. The spontaneous torque build-up and confident power delivery – which does not suffer from any interruption of tractive power – are combined with engine running characteristics which are totally free of vibration. Four motors, four wheels: the intelligent and permanent all-wheel drive of the electric SLS guarantees driving dynamics at the highest level, while at the same time providing the best possible active safety. Perfect traction is therefore ensured for all four driven wheels, whatever the weather conditions.
This very special gullwing is therefore able to "electrify" the driver with a completely unique, effortlessly superior and emotional super sports car driving sensation – and this is just at the prototype stage. In brief: the SLS AMG E-CELL is a true AMG too.
High-voltage lithium-ion battery provides 400 v and 40 Ah
The SLS AMG E-CELL drive incorporates a liquid-cooled high-voltage lithium-ion battery featuring a modular design with an energy content of 48 kWh and a capacity of 40 Ah. The maximum electric load potential of the battery, which consists of 324 lithium-ion polymer cells, is 480 kW, which is an absolute best value in the automotive sector. Another technical feature of this considerable performance is the intelligent parallel circuit of the individual battery modules – this also helps to maximise the safety, reliability and service life of the battery. The 400-volt battery is charged by means of targeted recuperation during braking whilst the car is being driven.
A high-performance electronic control system converts the direct current from the high-voltage battery into three-phase alternating current which is required for the synchronous motors and regulates the energy flow for all operating conditions. Two low-temperature cooling circuits ensure that the four electric motors and the power electronics are maintained at an even operating temperature.
A separate low-temperature circuit is responsible for cooling the high-voltage lithium-ion battery. In low external temperatures, the battery is quickly brought up to operating temperature with the aid of an electric heating element. This helps to preserve the overall service life of the battery. In extremely high external temperatures, the cooling circuit for the battery can be additionally boosted with the aid of the air conditioning system.
Optimum weight distribution and low centre of gravity
The purely electric drive system was factored into the equation as early as the concept phase when the gullwing model was being developed. It is ideally packaged for the integration of the high-performance, zero-emission technology: by way of example, the four electric motors and the two transmissions can be positioned as close to the four wheels as possible and very low down in the vehicle. The same applies to the modular high-current battery, whose modules are located in front of the firewall, in the centre tunnel and behind the seats. Advantages of this solution include the vehicle's low centre of gravity and balanced weight distribution – ideal conditions for optimum handling, which the electrically-powered SLS AMG shares with its petrol-driven sister model.
The installation of the drive components required no changes whatsoever to the gullwing model's weight-optimised aluminium spaceframe. And there were just as few constraints when it came to maintaining the excellent level of passive safety and high degree of long-distance comfort that are hallmarks of Mercedes cars.
New front axle design with pushrod damper struts
The additional front-wheel drive called for a newly designed front axle: unlike the series production vehicle with AMG V8 engine, which has a double wishbone axle, the SLS AMG E-CELL features an independent multilink suspension with pushrod damper struts. This is because the vertically-arranged damper struts in the series SLS had to make way for the additional drive shafts. As is usual in a wide variety of racing vehicles, horizontal damper struts are now used, which are operated via separate push rods and transfer levers.
Thanks to this sophisticated front-axle design, which has already been tried and tested in the world of motor sport, the agility and driving dynamics of the electrically-powered SLS AMG attain the same high levels as the V8 variant. Another distinguishing feature is the speed-sensitive power steering with rack-and-pinion steering gear: the power assistance is implemented electrohydraulically rather than just hydraulically.
AMG ceramic composite brakes for perfect deceleration
The technology vehicle is slowed with the aid of AMG ceramic composite brakes, available as an optional extra for the series production model, which boast extremely short stopping distances, a precise actuation point and outstanding fade
resistance, even in extreme operating conditions. The over-sized discs – measuring 402 x 39 mm at the front and 360 x 32 mm at the rear – are made of carbon fibre-strengthened ceramic, feature an integral design all round and are connected to an aluminium bowl in a radially floating arrangement.
The ceramic brake discs are 40 percent lighter in weight than the conventional, grey cast iron brake discs. The reduction in unsprung masses not only improves handling dynamics and agility, but also ride comfort and tyre grip. The lower rotating masses at the front axle also ensure a more direct steering response – which is particularly noticeable when taking motorway bends at high speed. The ABS and ESP systems have been adapted to match the special application spectrum of the permanent all-wheel drive.
Full-LED headlamps and automatically extending front splitter
The purist, exciting design of the technology vehicle boasts a number of minor yet extremely effective modifications. At the front, the dynamically shaped full-LED headlamps with integrated daytime driving lights immediately catch the eye: they help to optimise the vehicle's energy efficiency, since they require less power compared with regular bi-xenon light systems. The wider radiator grille also has a new look, and now comes with transverse slats instead of a diamond-pattern grille. The air outlet openings on the bonnet and the vehicle sides have also been modified for enhanced aerodynamics. All trim and detachable parts, which are finished in chrome or silver shadow on the standard SLS AMG, are now finished in matt black.
The front apron has not only been brought further forward, but also helps to guarantee an optimised airflow in the area of the underbody. This improves air resistance while reducing downforce. An extendable front splitter enhances this effect: in parallel with the automatic rear spoiler, it extends downwards by seven centimetres at speeds above 120 km/h and helps to further accelerate the air which travels beneath the car. When it reaches the area of the rear axle, the air enters the rear diffusor which, due to the lack of an exhaust system, features a steeper angle, thus increasing downforce at the rear axle and in turn further enhancing the aerodynamic balance. The vehicle's AMG 10-spoke light-alloy wheels featuring a new, smooth-surfaced design are fitted with 265/35 R 19 (front) and 295/30 R 20 (rear) tyres.
Interior with new display instruments for electric drive
The transformation from petrol to electric super sports car also called for some specific changes to the interior. As a result, the AMG instrument cluster and centre console in particular both feature a new design. The new AMG instrument cluster provides information on speed, charge status of the battery and the estimated range. The newly designed centre console now houses a 25 cm touchscreen, which driver and passenger can use to conveniently operate all of the audio, climate and navigation functions, and also obtain information on the flow of power from the four electric motors.
The AMG Drive Unit, which is angled towards the driver, houses buttons for starting the motor, and the ESP functions, the AMG memory function and the extendable front splitter and rear spoiler. Using three new buttons, the driver can switch simply between P, R and D. The park setting is also enabled automatically by switching the electric motors off.
The interior appointments are dominated by high-quality nappa leather in a black/white colour combination – it has been used not only on the sports seats, the performance leather/alcantara steering wheel and the door linings, but also on the broad centre tunnel which runs towards the back of the vehicle between the seats.
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