BMW Vision EfficientDynamics Hybrid Concept
By Bill Siuru
BMW is debuting a Vision EfficientDynamics concept vehicle at the 2008 Geneva Motor Show. Based on the X5 Sport Activity Vehicle (SAV), this mild hybrid combines BMW’s 123d twin-turbocharged diesel engine with an electric motor, lithium-ion battery pack, and roof-mounted solar panel.
Part of the BMW EfficientDynamics program, this concept vehicle is the first application of a four-cylinder diesel engine with BMW ActiveHybrid technology in a large SAV. Here, the 2.0-liter, four-cylinder diesel engine supplies a maximum output of 204 horsepower and the 15-kilowatt motor adds 17 hp more, for a total of 221 hp.
Output from both engine and motor is sent to all four wheels through a ZF eight-speed automatic transmission, with BMW's xDrive torque vectoring all-wheel-drive. The transmission, developed jointly by BMW and ZF Getriebe GmbH, is ready for serial production. This 8-speed automatic helps reduce fuel consumption and exhaust emissions through its direct connection to the engine and minimized torque-converter slip. BMW’s xDrive intelligent all-wheel-drive system divides power variably between the front and rear axles.
The concept uses two parallel vehicle electrical systems, a conventional 12 volt system supplied by the AGM starter battery and an additional 120 volt system that’s supplied by a generator and lithium-ion battery pack located in the luggage compartment. Rather than a conventional engine-driven generator, a compact generator is integrated in the aluminum crankcase housing. The high-power electronic system is flange-mounted directly onto the gearbox for a more compact design. Brake Energy Regeneration helps charge the battery.
A high-power, one square meter solar panel on the roof provides up to one kilowatt-hour of energy and preheats the transmission fluid to reduce friction during a cold start. After startup, the solar panel helps power accessories, particularly during idle when auto start/stop is functioning. During standstill it’s designed to provide electricity for the climate control system, infotainment, phone charging, or the vehicle’s battery charger.
Even the wheel rims were designed to help reduce fuel consumption in the interest of optimizing efficiency. The aerodynamic shaping of the spokes reduces rim ventilation power requirements by one kilowatt at 100 mph.
Mild hybrid technology allows this 5,000 pound SAV to turn in 36 mpg on the EU combined cycle while providing BMW-like performance, including 0 to 60 mph acceleration of 8.9 seconds. Carbon dioxide emissions are rated at 172g/km.
The hybrid module is based on technology developed as part of the hybrid co-operation project between BMW and Daimler. Besides this mild hybrid four-cylinder diesel application, the BMW Vision EfficientDynamics components are used with a full hybrid and V-8 gasoline engine in the BMW Concept X6 ActiveHybrid. The technology could appear in a production BMW as early as 2009.
Want to know more about diesel hybrids? Be sure to check out these articles on GreenCar.com:
GM Unveils Opel Flextreme Diesel-Electric Hybrid
Hybrid BMW X3 Compact SUV
Mercury Meta One Diesel Electric Hybrid
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