A little more than a year ago, the all-electric Mini E stole the limelight at the 2008 Los Angeles Auto Show. Now, BMW has released details of its next all-electric concept car, which will formally debut at next month's Detroit Auto Show.

The BMW Concept ActiveE electric car is based on the BMW 1-Series Coupe, and it's a full four-seater. That contrasts with the Mini E, whose back-seat space was largely taken up by the large lithium-ion battery pack.

In fact, says BMW, the passenger compartment is identical to that of a liquid-fueled 1-Series Coupe, with no changes in the head, leg, and shoulder space dimensions. The Concept ActiveE adds a few unique styling touches to what is recognizably a 1-Series Coupe, with a closed rear apron (no exhaust pipe!), aerodynamic alloy wheels, and blue accents including a blue ring in the tire sidewall.

2009 BMW Concept ActiveE

2009 BMW Concept ActiveE

Rear motor, rear-wheel-drive

The ActiveE is rear-wheel-drive, as are all BMW sedans, with a 125-kilowatt (170-horsepower) electric motor in the rear axle. Though the power electronics sitting on top of the electric motor reduce trunk volume, there's still 7 cubic feet of space in the trunk, which BMW notes is larger than that of the 1-Series convertible--making the Concept ActiveE clearly more practical than the electric Mini was.

Regenerative braking is integrated into the rear wheels, turning the electric motor into a generator when the driver lifts off the accelerator. BMW says up to 75 percent of all deceleration occurs without using the brakes, recapturing 20 percent of the battery's energy. When greater brake force is required, pressing the brake pedal engages the friction brakes just as in a standard BMW.

2009 BMW Concept ActiveE

2009 BMW Concept ActiveE

Jointly developed battery pack

The battery pack used in the BMW Concept ActiveE  is a joint effort among BMW, Bosch, and Samsung, which supplied the lithium-ion cells in a format specially made for automotive use. The Mini E, on the other hand, lashed together thousands of "commodity" small lithium cells, of the kind used in mobile phones and laptop computers.

The liquid-cooled pack is actually split among three locations: where the gasoline tank would sit under the rear seat, in the tunnel formerly occupied by a propeller shaft, and in the former engine compartment. Oddly, BMW does not specify the total energy capacity of the entire pack.

2009 BMW Concept ActiveE

2009 BMW Concept ActiveE

But the distributed pack preserves a 50-50 weight ratio, and the center of gravity in the concept is lower than in a gasoline- or diesel-fueled 1-Series. Total vehicle weight is about 3,900 pounds.

100-mile range

BMW promises an electric range of roughly 100 miles, and quotes a 0-to-62-mph time of 8.5 seconds. Maximum speed is limited to 90 miles per hour. Charging time is said to be 3 hours in Europe (using a 50-ampere circuit at 230/240 Volts), and about 4.5 hours in North America (on a 32-amp circuit providing the 220-Volt current used in electric stoves or clothes driers).

2009 BMW Concept ActiveE

2009 BMW Concept ActiveE

Like the Mini E, BMW plans to put real-world drivers behind the wheel of these emissions-free sports sedans. The goal is the same: to gather actual data on how drivers use electric cars in everyday travel.

Battery charge via mobile device

One way to gather data will be the BMW ConnectedDrive application, which integrates destination and routing info with data from the car itself on the condition of its systems, including the all-important battery state of charge and remaining range.

2009 BMW Concept ActiveE

2009 BMW Concept ActiveE

This will eventually let drivers integrate quick-charging locations into their travels, whether at an Interstate rest stop or the parking lot of a local big-box store. Meanwhile, they can get instant updates on battery charge via their mobile devices.

The real-world data it collects, promises BMW, will be used in the creation of a fully electric vehicle that will go on sale during the first half of the coming decade. It will not be sold by a new brand, but "under a sub-brand of BMW".

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