BMW revealed at the 2009 Frankfurt Motor Show the most extreme interpretation of its EfficientDynamics program with the Vision EfficientDynamics concept car. In a break with tradition of recent times, BMW has not based its latest clean concept vehicle on a production model but instead chosen a 2+2 sports car.
Klaus Draeger, Member of the Board of Management of BMW AG, Development, explained the thought process behind the creation of the car: “We wanted to know what would happen if we took EfficientDynamics to a new dimension. What we have created sets a new standard in sheer driving pleasure and shows that individual mobility definitely has a future.”
Vision EfficientDynamics combines the performance a BMW M vehicle with the economy and emissions of a smaller car. There are three sources that contribute to the total power figure of 356 bhp (262 kW): a three-cylinder diesel engine, a hybrid synchronous motor on the front wheels, and a full hybrid system at the rear.
BMW has followed in the footsteps of Volkswagen by using downsizing, the car’s diesel engine displacing 1.5 L but able to produce 163 bhp (122 kW) and 290 N·m (214 lb·ft). These figures are achieved in part thanks to common-rail injection as well as the use of a turbocharger with variable intake geometry.
The hybrid system on the rear axle is a development of the system used on the ActiveHybrid 7 production model. Operating as an electric motor, the unit sits between the diesel engine and the transmission developing a constant 25 kW and peak 38 kW.
The third motor powers the front wheels. It produces permanent output of 60 kW and a peak torque of 220 N·m (162 lb·ft). An extra 84 kW is available for 30 s, while Vision EfficientDynamics can run in full electric mode, albeit only for 10 s. During this time the power pack of 98 lithium-polymer cells help to generate 104 kW.
BMW says this latest development of the lithium-ion battery was used as it offers the most efficient technology for storing the highest level of electrical energy possible for optimum performance. Each of the cells boasts a capacity of 80 A·h and delivers continuous output of 600 A at 3.7 V.
The BMW concept also offers plug-in capabilities, a connector being located under the right front wing of the car. Using a domestic power source, the lithium-polymer cells are fully charged in a maximum of 2.5 h; using a source with higher voltage and amperage can reduce that time to just 44 min.
The combination of the three power sources ensure a limited top speed of 155 mph (250 km/h) and a 0-100 km/h (0-62 mph) time of 4.8 s. Average fuel consumption is figured at 3.8 L/100 km, while CO2 emissions are rated at just 99 g/100 km.
BMW has leaned on its Formula 1 expertise to hone the car’s aerodynamics. A number of the elements on the body serve as air deflectors, such as the A pillars, which are designed as air ducts and channel the flow of air. The car’s underbody is completely covered, avoiding air turbulence that could increase fuel consumption.
Further optimization of the car to help reach a drag coefficient of 0.22 is made with the adoption of 195/55 tires placed on 21-in rims. These wheels provide a contact surface that is only normally offered by a wider tire.