Big but green

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, and all shrouded in a BMW X5 body.

All of these technologies combine to deliver the best fuel economy and lowest emissions of any large 4x4 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 in the BMW Vision EfficientDynamics 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. As a consequence, it delivers nearly the same levels of horsepower as the conventional X5, but offers improvements in its already class-leading consumption and emissions figures.

The mild hybrid solution in the BMW Vision EfficientDynamics 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. Innovatively, 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.

The power harnessed by the batteries is also supplemented by roof mounted photovoltaic solar panels, measuring 1.0 metre square. The energy generated can either be used immediately or stored for later use. Importantly, the power created in this zero- CO2 way can be used to pre-heat the diesel fuel. The less efficient warm-up phase is thus shortened considerably.

This innovative and technologically advanced engine is directly mated to a new eight- speed automatic transmission. Developed jointly between BMW and ZF, the new gearbox delivers fast and efficient gear changes.

[IMG]http://www.oneshift.com/showroom/uploadimages/resized-20080222103736950.jpg[/IMG]

[IMG]http://www.oneshift.com/showroom/uploadimages/resized-20080222103753060.jpg[/IMG]

Credits: Jarvis