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BMW 7-series concept: Fast lithium-ion hybrid

The 7-series concept is a lithium-ion powered luxury saloon that promises decent fuel economy, good looks and a tonne of interesting gadgets inside

Last week, Mercedes unveiled the S400 BlueHybrid, a hybrid concept car powered by lithium-ion batteries. This week it's BMW's turn, with the new 7-series concept -- a luxury saloon that promises decent fuel economy, good looks and a tonne of interesting gadgets inside.

The first thing that struck us about this car is the amount of power and torque it claims. It's set to use a twin-turbo V8 engine that delivers 407bhp and 442 pound-feet of torque. By adding an electric motor to the equation, power is boosted to 427bhp and torque to an incredible 597 pound-feet. Even the McLaren F1 only had 479 pound-feet of torque, although to its credit, it is a heck of a lot lighter.

Like the Merc S400 BlueHybrid, the BMW concept 7 series' electric motor runs on lithium-ion batteries, which are lighter and more efficient than the nickel metal-hydride cells found in a Prius. This forms part of the car's idle-stop system, which allows the petrol engine to shut off at traffic lights and re-start seamlessly when you pull away, maintaining high torque in the process. Although no official mpg figures have been released, BMW reckons this approach improves fuel economy by up to 15 per cent.

True to 7-series tradition, the new concept promises plenty of cool tech, including rear-wheel steering, doors that physically shut themselves, digital TV, voice control and a wealth more. Expect this car, and a hybrid version of the BMW X6, to reach production in 2009. -Rory Reid