The diesel engine is just part of the efficiency equation, however. An electric generator is housed in the transmission and can contribute 15 kW of power and up to 155 lb-ft of torque. When added to the engine output, the hybrid system peaks at 221 hp. Generated electricity is stored in a lithium-ion battery that's mounted in the luggage compartment. The vehicle can recover energy with regenerative braking and store additional "free" energy from the sun via a roof-mounted solar panel. Accessories like power steering, the air conditioning compressor, and engine coolant pump run on a 120-volt system that takes advantage of stored power and frees the engine up to move the X5 down the road (with a 0-to-62-mph time of 8.9 seconds).
Those ideas may foretell what's in BMW's hybrid future, but the concept's new gearbox is production-ready. An eight-speed automatic transmission was co-developed with ZF and goes along with the EfficientDynamics theme. The extra gears give a wide range of ratios while an electronic gear-finder makes skipping the unnecessary ones possible. Locking the transmission to the engine - accomplished by a clutch that engages once the vehicle is moving -reduces driveline losses.
While the concept shows what's possible (albeit hidden under a normal-looking X5), BMW warns that such improvements in efficiency "can only be achieved by means of an exponential increase in effort and expense." Translation: prepare to pay a premium if you want to save the earth in BMW style.
BMW Vision Efficient Dynamics X5
BMW Vision Efficient Dynamics X5
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