BMW 1-series ActiveE, an Autoweek Flash Drive Car Review

BMW's first series production electric car, the 1-series ActiveE, is coming in limited numbers to the United States in December. BMW says it will build no more than 1,100 copies of the car.

To be offered to customers on a two-year/31,000-mile lease similar to that of the earlier BMW-engineered Mini E, the zero-emissions coupe acts as a technological test bed for BMW's upcoming i3--a compact four-door hatchback previewed in concept form at the recent Frankfurt motor show. It's set to go on sale in 2013.

Unlike the two-seat Mini E, which relied largely on off-the-shelf electric-drive technology and was developed with the help of U.S. firm AC Propulsion, the four-seat 1-series ActiveE was conceived wholly in-house at BMW's Munich, Germany, R&D center. BMW worked closely with a series of system suppliers it says will play an important role in the new "i" brand and its initial i3 and i8 models. Many of the driveline components are unique.

The 1-series coupe was heavily modified to accommodate the ActiveE's electric drive system. Among the more significant changes is a new crash structure up front, an altered transmission tunnel down the middle of the steel floorpan, a reworked rear-end structure and a completely revised rear-axle assembly.

Power comes from an electric motor mounted at the rear, in the space usually taken up by the differential of the standard 1-series. Produced at BMW's Dingolfing factory in Germany, the brushless unit produces 170 hp and 184 lb-ft of torque the moment you depress the throttle--33 hp less but 24 lb-ft more than the Mini E's electric drive system.

By comparison, the 128i's naturally aspirated 3.0-liter inline six-cylinder gasoline engine delivers 230 hp and 230 lb-ft of torque.

Electrical energy to run the motor is provided by three separate banks of lithium-ion batteries mounted under the hood, down the center line of the floorpan within the altered transmission tunnel and under the rear seat. Together they have an overall capacity of 32 kilowatt-hours and provide a peak current of 400 amps.

The battery cells hail from a joint-venture company created by Korean giant Samsung and German-based electronics specialist Bosch called SB LiMotive. The control electrics, the brains of the whole system, are located in the trunk. Cargo capacity is cut nearly in half, to just seven cubic feet.

In a move BMW says was prompted by lessons learned with the Mini E, the batteries receive liquid cooling to ensure constant performance in all climates. Recharging is via a plug-in socket located behind the traditional fuel-door flap. Using the 32-amp charger that BMW offers as part of the 1-series ActiveE lease deal, the company claims recharging takes between four and five hours on a standard outlet.

Drive is channeled to the rear wheels via a single-speed transmission.

Despite the investment BMW has made into lightweight construction technology with its new i brand, the 1-series ActiveE retains an all-steel body shell without any aluminum or carbon fiber to help trim pounds. The standard rear bench seat was, however, exchanged for the seat used in the 1-series M coupe, which is claimed to save 11 pounds. Still, the new car's curb weight is put at a portly 4,001 pounds.