Battery-electric drive systems offer a wealth of advantages in this respect: they provide a high level of torque, are compact and quiet, run extremely efficiently and with zero local emissions, and they operate without the need for fossil fuels. However, it is not currently possible to fulfil all mobility requirements with a single electric vehicle concept. Those who drive predominantly or even exclusively in urban areas do not place as much emphasis on vehicle range but very much like the idea of lower noise levels and emissions. For such customers, a battery-electric vehicle is an attractive solution.
Those who also wish to cover long distances on country roads and motorways combined with low noise levels, no local emissions and short refuelling times have a viable alternative in the shape of the fuel-cell electric vehicle. This technology clearly shows the way ahead in terms of sustainable mobility after the „crude oil age“ but requires a hydrogen-fuel-supply infrastructure. The beneficial combination of maximum range, fast energy storage on board from an existing infrastructure as well as noiseless and locally emission-free mobility in urban areas is offered by a battery vehicle with range extender.
The sandwich-floor architecture and the modular design allow three different drive configurations that are able to meet an extremely wide range of different requirements. Measuring 4.22 m in length, 1.89 m in width and 1.59 m in height, the extremely compact BlueZERO concept offers decisive design advantages over electric cars based on conventional vehicle platforms and designed only for use in combination with internal combustion engines.
Furthermore, all three BlueZERO electric cars are highly suitable for electromobility in urban areas on account of their compact dimensions, easy entry and exit, raised sitting position and optimal all-round visibility. All of which makes Mercedes-Benz the first and, to date, only car manufacturer in the world to offer three optimal solutions that meet all customer electromobility requirements.
Featuring a modified version of the sandwich-floor platform, the BlueZERO concept sets standards for the electric car sector in all areas relevant to day-to-day motoring. The best possible crash safety is assured as almost all of the drive components are housed within the sandwich floor, that is to say in the protected area between the axles.
Typically for this class of car, all three versions of the Concept BlueZERO are front-wheel drive models with an electric motor at the front axle. The batteries are located in the centre of the vehicle floor behind this, in a position which protects against intrusion in the event of a frontal or rear impact because the energy accumulators are located outside of the body’s impact and deformation zones. Furthermore, the extremely robust construction of the sandwich floor can offer a high level of protection for both the battery and the occupants, even in the event of a side collision. This advantage is also of economic benefit as the battery is the largest cost factor in electric drive systems. Consequently, if the battery remains undamaged in an accident, the follow-up costs are reduced considerably. By virtue of its proven nutshell effect, the sandwich floor is the safest place for housing the still relatively expensive energy accumulators.
Mercedes-Benz will present two BlueZERO variants at the 2009 NAIAS show in Detroit: the BlueZERO E-CELL as a purely battery-powered vehicle and the fuel-cell version, the BlueZERO F-CELL – both of which are emission-free in local operation. Mercedes-Benz development engineers are also working on a third version with a range extender, the BlueZERO E-CELL PLUS. This is additionally equipped with a compact internal combustion engine as a generator that produces power during a journey.
All these models feature battery packs based on the latest lithium-ion technology. This new battery technology has decisive advantages over conventional battery types, among them very compact dimensions, significantly higher performance, excellent reliability and a long operating life. The common components used in the modular system also include the compact, permanent magnet synchronous electric motor, which operates at a maximum of 13,280 rpm. It develops a peak output of 100 kW and a continuous output of 70 kW. Its peak torque is 320 Nm, while the continuous torque is 180 Nm. The maximum torque is available from the first revolution of the electric motor and exceeds the figure achieved by a current V6 petrol engine at 2500 rpm.
BlueZERO E-CELL: agile, quiet and locally emission-free
The BlueZERO E-CELL is equipped with a lithium-ion battery with a capacity of 35 kilowatt hours (kWh). The liquid-cooled high-voltage cells have an operating voltage of 240 to 426 V. With this battery the BlueZERO E-CELL has an operating range of up to 248 miles. Recharging the empty battery takes three to four hours. The BlueZERO E-CELL accelerates from zero to 62 mph in less than eleven seconds and, in the interests of optimal range and energy efficiency, has an electronically limited top speed of 93 mph.
The new-generation fuel cell used in the BlueZERO F-CELL is more compact and – with a maximum output of 90 kW (continuous output 80 kW) – also more powerful than its predecessor. It can be cold-started at temperatures down to minus 25 degrees Celsius and also has the benefit of short refuelling times.
On the road, the BlueZERO F-CELL ensures a high standard of dynamic handling, yet this family-friendly compact returns a highly impressive 97.4 miles per gallon of fuel (diesel equivalent). According to the NEDC, the BlueZERO F-CELL is able to cover well over 248 miles on one tank of hydrogen.
In the fuel cell version of the BlueZERO, the electric motor, high-voltage battery and hydrogen tank are likewise positioned beneath the passenger cell to save space. The system uses the most efficient energy source for the current driving situation. When parking or manoeuvring at slow speed, for example, the electric motor uses only battery power. When accelerating, energy is provided by both the fuel cell and the battery. When braking, the electric motor acts as a generator and charges the battery. This efficient system therefore makes use of the energy that would be converted into heat during conventional braking and stores it in the powerful lithium-ion battery.
For longer journeys too, Mercedes-Benz sees the fuel cell as one of the key technologies for zero-emission driving. Providing a suitable network of hydrogen filling stations is in place, this technology offers ideal possibilities for sustainable mobility well into the future. The hydrogen-powered fuel cell combines „zero emissions“ with a long operating range as electrical power is generated on board during the journey. There are no exhaust emissions whatever, and no CO2 is emitted either. The BlueZERO F-CELL emits nothing more than steam. Moreover, a fuel cell drive system is almost twice as efficient as an internal combustion engine.
In the third version, the BlueZERO E-CELL PLUS, the Mercedes engineers combine the electric drive system from the purely battery driven BlueZERO E-CELL with an additional internal combustion engine that serves as a range extender. The compact 50-kW three-cylinder turbocharged petrol engine from the smart fortwo charges the battery whilst the car is being driven.
Advantage of the range extender: as with conventionally powered cars equipped with a petrol or diesel engine, the customer benefits from a significantly longer range (up to 370 miles), especially as the BlueZERO E-CELL PLUS can also be quickly and easily refuelled at any normal filling station. The customer can therefore be sure that the car is available for use anywhere and at any time. And when an urban area is reached after an overland journey, the driver can continue on their way under electric power alone.
The BlueZERO E-CELL PLUS therefore allows electric mobility at the touch of a button, a particular benefit in densely populated urban areas with environmental zones, toll charges and other access restrictions affecting cars with internal combustion engines.
The BlueZERO E-CELL PLUS with the range extender clearly highlights the advantages of the sandwich-floor platform: here too, the key drive components are integrated in the underfloor area to save space. The internal combustion engine is installed near the rear axle, in the spare wheel well. Thanks to the range extender, the BlueZERO E-CELL PLUS has a range of up to 370 miles, of which 93 miles are in locally emission-free electric mode, with no drop in performance. The NEDC fuel consumption is 62 mpg. In conjunction with a plug-in battery and the resulting CO2 bonus, the car emits just 32 grams of CO2 per kilometre.
In addition, the highly efficient modular concept allows further variants to be individually configured. If the system is designed appropriately, the internal combustion engine used as a range extender can also be temporarily used as a direct drive unit – when driving on country roads, for example. This setup leaves the full battery capacity available for driving in town. Other conceivable variants might be to use the fuel cell as a range extender, or a combination of the fuel cell and plug-in batteries. Thanks to this versatility, the Mercedes-Benz modular electric drive concept is able to cover every conceivable option for electric driving.
Instead of a fuel filler cap, the car features plug-in connectors to EU and US standards for rapid recharging with electrical power. One contact is designated for conventional power cables that fit any household power socket. The second contact is suitable for connection to public recharging stations.
Cutting-edge technology is very attractively packaged in all the BlueZERO variants. The future-oriented yet unmistakable Mercedes-style body contours accentuate the progressive nature of the Concept BlueZERO straight away.
The Mercedes-Benz designers have emphasised this aspiration by introducing paint finishes in three new ALU-BEAM colours. Each of the three variants makes its individual mark: the BlueZERO E-CELL is painted in a fresh lime green, while the BlueZERO F-CELL has mint green paintwork. Confidence-oozing orange was chosen for the BlueZERO E-CELL PLUS.
The striking character lines along the flanks give this compact concept car a very dynamic side line and accentuate its bionic structure. This characteristic feature of the Mercedes-Benz bionic car was adapted and modified for the Concept BlueZERO. These elements lend the body design its dramatic power.
The lower line emerges from the flank in the front doors at the height of the wheel hub, then rises gently to turn steeply upwards and harmoniously continue the body line to the tail lights. This has the effect of stretching the body in visual terms, while suggesting dynamic forward movement despite the comfortable vehicle height. The precisely placed edges break the light to striking effect and lend the BlueZERO a masculine character that is a hallmark of the new Mercedes-Benz design idiom.
Translucent surfaces make technology that is normally concealed visible. The light-grey tailgate is made completely from lightweight but highly robust Lexan that allows 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: the luggage compartment and passenger area are fully usable, as there are no technical components that need to be accommodated here.
Key features at the distinctive rear end of the BlueZERO models include tail lights in the form of a curved „L“, whose flame-like shape add a futuristic touch. In addition, the Mercedes designers have achieved a new-quality light production: four transparent lenses produce a red light curtain which tapers smoothly towards the sides, creating a lightly diffused effect.
This effect is repeated, albeit in white this time, by the front headlamps. What’s more, the front lights feature new lens technology and a plexiglass edge to produce „C“ shaped daytime driving lights with the help of state-of-the-art LED technology. The extremely energy-efficient LED technology offers the same brightness but requires ninety percent less power than conventional lights. The lenses are held by supports which also serve as direction indicators. Aerodynamic design with eye-catching effects
The radiator grille with its centrally located star and even more pronounced V-shape is a striking reinterpretation of the world-famous Mercedes-Benz radiator grille. The excellent aerodynamics of the BlueZERO are partly due to the closed front apron, whose design dispenses with any cooling air intakes. The 20-inch wheels are also aerodynamically optimised. Low-friction tyres reduce rolling resistance.
Like many other design features, the wheel covers are transparent and allow a view of wheel spokes, which are visually enhanced with three-dimensional light effects. All BlueZERO variants are also equipped with a semi-transparent, lightweight panoramic roof into which solar panels have been integrated. The thin-layer cells used here allow 20 percent of the light into the interior. Given enough sunlight, they generate sufficient electric power to charge mobile phones or mobile MP3-players, for example.
The interior features an all-new, progressive design idiom: the lines are curved and blend in subtly with the organic surfaces. The Concept BlueZERO is a logical continuation of the bionic design line and is similar to the Mercedes-Benz bionic car. A wealth of structures inspired by nature and modelled on organic growth can be found in several of the panelling components: in the door stowage areas, the cockpit, the centre console, the load compartment and the load sill guard.
The array of coloured transparent surfaces lends the interior a feeling of lightness. This is enhanced by semi-transparent surfaces whose edges form striking light breaks. This interplay between transparency and edge emphasis contrasts extremely well with the soft design idiom. The suggested fluorescent conductor paths in the centre console represent the advent of a future drive technology.
The sporty front seats feature seemingly inserted upholstery and dynamically shaped backrests. The overall impression is one of lightness and litheness, all of which makes the vehicle interior feel much more open. As a five-seater, the Concept BlueZERO offers the flexibility and functionality of a modern-day compact car.
The material concept is largely based on a tone-in-tone composition enriched by touches of colour. By way of example, the belt colour and the seam thread in the panelling components establish a link with the car’s exterior, while the leather strip in the seats creates a visual link with the high-quality steering wheel. Thanks to their surface quality, the materials are highly resistant. The material mix of textiles and plastics combines a high level of value with high-tech appeal.
With the BlueZERO concept studies, Mercedes-Benz provides a very specific outlook on the immediate future of electric motoring. Major components of this modular drive concept will shortly be used in standard-production cars made by Mercedes-Benz. These include the fuel cell drive system, which will enter small-scale production in 2009. In 2010, the first Mercedes-Benz electric car will also be introduced into small-scale production.
With this intelligently conceived modular system, Mercedes-Benz will also be able to realise tailor-made drive configurations for individual requirements in the electric car sector. For the brand’s customers, this means a wide choice of purpose-made, efficient and affordable solutions.
The product implementation presented by Mercedes-Benz on its „Road to the Future“ is uncompromisingly wedded to the modular design principle: modular drive technologies that can be used individually or in combination depending on vehicle class, operating profile and customer requirements which are a key factor in this.
This particularly applies to hybrid models such as the S 400 BlueHYBRID, which is due to be launched in 2009 as the most economical petrol-engined luxury saloon and CO2 champion in its class. For its hybrid models with petrol and diesel engines, Mercedes-Benz has developed a modular system which can be expanded with respect to performance and range of applications.
In the view of Mercedes-Benz, there will be no single technology as the ideal solution for sustainable mobility in the future. Instead the company is responding to the varied requirements with equally versatile solutions. The respective advantages of the individual technologies in terms of optimal fuel consumption and emission values are applied in specific application areas. Mercedes-Benz is basing its strategic planning for the future of individual mobility on the following mix of drive systems:
The electric drive configuration presented in the Concept BlueZERO does full justice to this requirement profile. Mercedes-Benz has conducted intensive research in the field of fuel cell technology since as early as 1991, and therefore has vast experience in the field of electromobility. The brand has the world’s largest fleet of fuel cell powered vehicles undergoing customer trials, for example. And in the field of battery-powered vehicles, the company has also gained unrivalled experience from fleet trials involving 100 smart electric drive cars in London. The Concept BlueZERO impressively reflects this in-depth know-how.