With the Concept BlueZERO Mercedes-Benz showed the way ahead in environmentally responsible electromobility at the North American International Auto Show (NAIAS) in Detroit in January 2009. This was a modular concept which, based on a common vehicle architecture, made three vehicles with different drive configurations possible. BlueZERO E-Cell led the way with a battery-electric drive, which permitted a range of up to 200 kilometres using electric drive alone. BlueZERO E-Cell PLUS also has a battery-electric drive system, with an additional internal combustion engine which acted as a generator (‘Range Extender'). The combination made a range of up to 600 kilometres possible (under electric power alone the range that could be achieved was 100 kilometres). The third concept was the BlueZERO F-Cell system with a fuel-cell that produced electric energy from hydrogen, enabling a range of up to 400 kilometres with one tankfull.
The three variants were based on the unique sandwich-floor architecture, which Mercedes-Benz introduced from the mid 1990s onwards, one of the aims being the integration of alternative drive systems for the A- and B-Classes. Advantages of the modified design included the fact that the relevant drive components were installed beneath the vehicle floor in a space-saving, protected location. In terms of lightweight construction, interior and bodywork design too, the five-seater BlueZERO studies also set standards.
All three variants shared the same key technical components, design and vehicle dimensions were also identical. Measuring just 4.22 metres, the BlueZERO models combined compact exterior dimensions with a generous interior and luggage compartment sizes. Five fully-fledged seats, a payload of around 450 kilos with a volume of 500 litres make for outstanding everyday practicality. Thanks to their sandwich construction with a raised seating position, they also offered extremely good crash safety for passengers and technical components as well as exceptional all-round visibility.
The Concept BlueZERO offered the following convincing advantages over electricity-powered cars based on conventional vehicle platforms and originally designed only for the use of internal combustion engines:
- Interior space offered by the vehicles was retained in full. Thanks to the integration of the drive components in the spacious sandwich floor, neither the passenger nor the luggage compartments had to suffer any reduction in size or variability whatsoever.
- The drive engineering components installed in the sandwich floor produced a low centre of gravity. This favoured a particularly reliable and agile handling.
- Thanks to the sandwich concept and the location of major drivetrain components between the axles, the vehicles' crash safety was of the accustomed high level typical of Mercedes‑Benz.
- As a result, the BlueZERO models were very different from conventionally-built electricity-powered vehicles, which had to accommodate heavy, bulky storage batteries in the boot or in the rear seat area.
All three BlueZERO models featured front-wheel drive, which is typical for this class of car. They had identical components, stemming from a modular construction principle, among these the liquid-cooled lithium-ion accumulator with a storage capacity of up to 35 kWh. The liquid-cooled high-voltage operated with a voltage of 240 to 426 volts, depending on the configuration. The compact permanent-magnet synchronous electric motor with a maximum output of 100 kW and a continuous output of 70 kW achieved a maximum rev speed of 13,280 rpm. It delivered a maximum torque of 320 newton metres and a continuous torque of 180 newton metres. All three variants were able to accelerate from a standstill to 100 km/h in less than 11 seconds. In the interests of achieving an optimum range and energy efficiency, the top speed was electronically limited to 150 km/h.
With a charge of 15 kW the lithium-ion batteries of the BlueZERO E-Cell and the BlueZERO E-Cell PLUS were able to store energy for a distance of 50 kilometres within 30 minutes. Operating under purely electrical energy a charging time of one hour and two hours were necessary to cover distances of 100 and 200 kilometres, respectively. With a charge of 7 kW, as that provided by a normal three-phase current connection, requires twice these charging times. But it was also possible to recharge the vehicles using a conventional household socket. For both these vehicles electronic systems were also planned to support the intelligent charging stations and billing systems.
The BlueZERO E-Cell PLUS was also equipped with the same 1.0-litre turbocharged internal-combustion engine as the smart fortwo, as an additional range extender. The compact three-cylinder engine, installed in the rear of the vehicle, delivered a continuous output of 50 kW at an engine speed of 3500 rpm, recharging – via an alternator of the same output – the 17.5 kWh lithium-ion battery while driving according to requirements. This enabled the vehicle to achieve a maximum range of 600 kilometres with one tankfull. The range under electric power alone was of up to 100 km. NEDC (New European Driving Cycle) consumption was 4.5 litres per 100 kilometres. In conjunction with a plug-in battery the vehicle could achieve a carbon dioxide emission level of just 32 grams per kilometre.
The new fuel cell generation used in the BlueZERO F-Cell was more compact yet with a maximum output of 90 kW (continuous output 80 kW) at the same time more efficient than its preceding version. Its cold-start capability extended down to 25 degrees below zero. In addition, the system was characterised by low recharging times. The BlueZERO F-Cell was capable of attaining a range considerably in excess of 400 kilometres (NEDC, New European Driving Cycle) without generating any local emissions.
In practise this compact family car met high handling dynamics standards, but only consumed 2.9 litres of fuel (diesel equivalent) per 100 kilometres. In this variant of the Concept BlueZERO, too, the drive system components (in this case electric motor, high-voltage battery and hydrogen tank) were located in a space-saving manner beneath the passenger compartment. The system used the most efficient energy source in each handling situation, so that the electric motor operated using only battery current when parking or manoeuvring. When accelerating both the electric battery and the fuel cell together delivered the required energy. When braking the electric motor acted as a generator, recharging the battery. This way, the efficient system made use of the energy which in conventional braking systems is converted into heat, storing the energy in the lithium-ion battery.
In all three BlueZERO variants, the pioneering technology was attractively packed in a homogenous manner. The independent and therefore unmistakably Mercedes-typical design language of the vehicle body showed the advanced character of the concept vehicles at first glance.
The front end, radiating powerful elegance, characterised the radiator grille with its centrally-located star. Good aerodynamics were aided by, among other things, the vehicle's closed front apron whose design allowed it to dispense with cooling air intakes. The 20-inch wheels were likewise aerodynamically optimised, while rolling-resistance-optimised light-running tyres reduced rolling resistance.
The striking feature line on the vehicle's flanks lent it a very dynamic side line and underscored the bionic (biological and technical) structure as a model of biological functions borrowed from Nature. This stylistic feature of the Mercedes-Benz bionic car, which appeared in 2005, was adapted and further developed for the BlueZERO models. These elements gave the bodywork a feel of powerful tension.
The remarkable rear-end view of the concept vehicles was characterised by the tail lamps in the shape of an elegantly curved ‘L'. The designers implemented here a new quality of light production: transparent lenses created a light curtain that tapers smoothly towards the sides, creating a lightly diffused effect. This created a slightly diffuse effect. This effect was repeated in the headlamps, albeit in white. In addition, the front lights featured new lens technology and a plexiglass edge to produce ‘C' shaped daytime driving lights with the help of state-of-the-art LED technology.
Translucent surfaces make the normally concealed technology visible. The light-gray tailgate is made completely from lightweight but highly robust Lexan, allowing a view of the aluminium structure that makes up the rigidifying frame, for example. At the same time, this transparent tailgate provides a view of the vehicle interior, making the advantages of the sandwich-floor platform obvious at a glance: for maximum customer benefit, the luggage compartment and passenger area remain fully usable, since there are no technical components that need to be accommodated here.
The comprehensive claims of the concept vehicles were underlined by the Mercedes-Benz designer– among other things – with the colour scheme in three new ALU-BEAM colour tones. Each one of the three variants had its own individual focus: the BlueZERO E-Cell had a fresh ALU-BEAM yellow paint finish, the BlueZERO F-Cell presented itself in ALU-BEAM green. And finally, the designers chose a self-assured ALU-BEAM orange for the BlueZERO E-Cell PLUS.
The vehicles' wheel caps were transparent, as were many other design elements, allowing the wheel spokes to become visible with the three-dimensional light effects that highlighted them. In addition, all three variants were equipped with a semi-transparent lightweight panorama roof with integrated solar panels. The thin layer cells used in them allowed 20 per cent of incident light through into the vehicle interior. Under adequate insolation conditions a current could be generated that was sufficient to charge a mobile telephone or a mobile MP3 player.
The interior was designed with a fully new progressive form language: lines flowed curved and subtle in the organic surfaces. The Concept BlueZERO was coherently based on bionic design principles and on the Mercedes-Benz bionic car. Numerous structures borrowed from Nature, recreating organic growth, were to be found in diverse trim components: in the door stowage compartments, the dashboard, the centre console, the luggage compartment and in the loading sill protection.
The many coloured transparent surfaces lent the interior a feeling of lightness. This was achieved by semi-transparent surfaces whose edges produced striking light refractions. This interplay between transparence and surface edge refractions underscored in a contrasting manner the smooth design language. The fluorescent glowing conductor paths in the centre console represented the entry into a drive system concept of the future.
The front seats, of sporty design featured optical seat cushion inserts with dynamically-shaped seat backrests. The overall effect was of lightness and slenderness, making the vehicle interior perceptibly more open. The five-seater concept vehicles offered the same flexibility and functionality as contemporary compact cars.
The material concept was based largely on a tone-in-tone composition, enriched by colour highlights: for instance, the seat belt colour and the topstitching in the trim elements signalled a connection with the vehicle exterior. The leather strip insets in the seats formed a visual bridge to the steering wheel, clad in haptically high-class leather. Thanks to their high surface quality, the materials were extremely hard-wearing. A material mix between textiles and plastics combined high quality with high-tech appeal.
With the BlueZERO concept studies, Mercedes-Benz provided a very concrete view of the future prospects for electric drive systems. Basic components of the modular drive concept were conceived for future series-production vehicles from Mercedes-Benz. The modular building-block system enabled tailor-made drive solutions for individual requirements to be designed. A first result was the Mercedes-Benz B-Class F‑Cell with a fuel cell- powered drive system that started series production in 2009.
Source: Mercedes-Benz
