BMW Vision EfficientDynamicsFebruary 22, 2008
The BMW Vision EfficientDynamics is a concept car designed to showcase the future direction of BMW’s performance enhancing and emissions lowering innovations. Mild ActiveHybrid technology is combined with a twin-turbocharged four-cylinder diesel engine, a new eight-speed automatic gearbox and even roof-mounted solar panels, all within a BMW X5 body. The world premiere will be at the Geneva Motor Show (4 – 16 March).
All of these technologies combine to deliver the best fuel economy and lowest emissions of any large 4×4 currently on sale. The BMW Vision EfficientDynamics delivers 43.5mpg on the combined cycle and just 172g/km of CO2 emissions. However with its twin-turbocharged two-litre diesel engine delivering more than 100hp per litre, the BMW Vision EfficientDynamics concept completes the sprint from zero to 62mph in just 8.9 seconds.
The 2.0-litre four-cylinder diesel engine uses BMW’s Variable Twin Turbo concept, third-generation common-rail injection and an all aluminium crankcase to deliver 204hp and 400Nm of torque between 2,000 and 2,250rpm. The engine is supplemented by a mild hybrid concept that delivers a further 20hp and 210Nm of torque under acceleration. Even though the BMW Vision EfficientDynamics features a relatively small capacity engine, it delivers nearly the same levels of horsepower as the conventional X5, but offers improvements in its consumption and emissions figures.
The mild hybrid solution uses a compact generator that, for the first time, is flange mounted directly onto the gearbox. This motor produces up to 20hp of on-demand power. In addition, BMW’s now familiar Brake Energy Regeneration is used to efficiently capture energy that would previously have been lost when the engine is on overrun. The alternator is also integrated into the crankcase rather than conventionally driven from the front of the engine.
BMW’s concept uses highly efficient lithium-ion batteries in the boot area to store the power generated. These high-storage-capacity batteries enable optimum use of Brake Energy Regeneration. In addition, they create possibilities to power the air conditioning, electric coolant pump and the electric power steering system. For these functions, a 120 volt vehicle power system was designed and runs in parallel with the conventional 12 volt system.
The power harnessed by the batteries is also supplemented by roof mounted photovoltaic solar panels, measuring one metre square. The energy generated can either be used immediately or stored for later use. The power created in this zero-CO2 way can be used to pre-heat the diesel fuel, so shortening the less efficient warm-up phase.
The engine is directly mated to a new automatic transmission with eight gears, which plays its part in improving fuel consumption and minimising emissions.
The chassis and ride-height of the X5 have also been adapted for this concept. This includes aerodynamically-efficient 19-inch light alloy wheels with reduced ventilation; the design of the spokes reduces wind resistance.
There’s no word about when we’ll see the Vision EfficientDynamics in production, but with the imminent London Congestion Charge changes, perhaps it will be sooner than we think.