Wednesday, October 27, 2010

BMW’s Green Sports Car

BMW Vision EfficientDynamics

“It’s the sports car of the future, the way BMW imagines it.” That’s how Adrian van Hooydonk, director of BMW’s group design, describes the “BMW Vision Efficient Dynamics” two-door concept vehicle to be unveiled at the upcoming Frankfurt Auto Show. Think of it as a showcase of the many fuel-efficient technologies that BMW has in various stages of development. Some of the technologies already appear in production vehicles, while the feasibility of rolling out other systems stretch the future to the point of never.

BMW’s overarching goal was to combine breath-taking speed and groundbreaking efficiency. In the BMW Vision, that boils down to 4.8-second 0-to-60 miles per hour acceleration and 63 mile to the gallon.

BMW Vision EfficientDynamics

First, BMW engineers use the rear-axle to combine a turbo-charged small diesel engine and the mildest forms of hybrid technology. That kind of combo comes standard in BMW 1-series cars in Europe. The Vision's setup is a little more similar to the BMW 320d, also to debut in Frankfurt, which uses a 2.0-liter four-cylinder diesel to deliver 162 horsepower, while promising more than 57 miles to the gallon. The BMW Vision takes it a step further by downsizing the engine to a 1.5-liter three-cylinder diesel engine mated with the more robust hybrid system found in the pricey BMW ActiveHybrid7, expected in the US early next year.

Not satisfied with 162 horsepower, BMW adds a second motor to drive the front wheels exclusively by electricity. When both motors and the diesel engine are called into service, the overall system can put out 356 horsepower. The BMW Vision is lightweight and aerodynamic. The design features an aluminum chassis and suspension, and an outer skin made mostly of polycarbonate glass. The car’s slippery design boasts a drag coefficient of 0.22—beating out the Toyota Prius’s 0.25.

BMW Vision EfficientDynamics

To mitigate the fuel efficiency penalty paid for power, the BMW Vision utilizes plug-in hybrid technology. This is where the Vision becomes more of a fantasy. The combination of diesel and hybrid technologies is widely viewed as cost prohibitive. Adding enough battery power to allow the BMW Vision EfficientDynamics to travel for 30 miles of all-electric drive, as BMW is promising, would send costs through the roof.

BMW also indicates that the Vision only needs a 187-pound 10.8 kWh battery to achieve the 30-mile all-electric goal. To pull that off, the Vision, according to BMW, will discharge the battery pack's capacity by 80 percent, which is likely to significantly reduce the longevity of the battery. (The Chevy Volt will use about 50 percent of its capacity to help ensure a lifetime of use.)