According to sources close to BMW, the German automaker is reputedly working on five models to premiere at the 2011 Frankfurt Auto Show in September, including its long-awaited i3 electric car.

BMW has kept details of its first mass-produced electric car quiet, although the ongoing stream of information on the car now in the public domain details a plausible set of specifications: a 112 kilowatt motor married to BMW’s preferred rear-wheel system, a battery pack capable of providing at least 100 miles of range per charge, and a price-tag of around $35,000.

Given these specifications, the BMW i3 sits at the top end of the same price-range and specification set as many electric cars already on the market, including the 2011 Nissan Leaf and 2011 Chevrolet Volt.

But unlike most cars on the market today, the i3’s body and internal components will be made almost entirely of lightweight composite materials to keep the car’s weight down.  Gone are the steel and aluminum panels of mainstream cars and in its place, carbon-fiber plastic and other tough-but-lightweight materials.

Shedding pounds in the frame and boy means a lighter car, and a lighter car means a more energy efficient car, so expect the i3 to produce some impressive fuel economy figures when it finally launches in time for the 2013 model year.

Before you get excited about the other four models reputedly debuting in Frankfurt we should probably point out that the i3 will be the only pure electric model. Alongside it, more conventional gas-guzzling BMWs, including a new M5 with a 555 HP twin-turbo V8, a face-lifted 1-Series, and a new V8-powered M3GTS.

BMW has yet to officially confirm that it will be unveiling the i3 at the Frankfurt Auto Show, but given that its 1-series derived ActiveE is scheduled to enter public lease trails in selected markets later this year we think the likelihood we’ll see the i3 this Fall is pretty high.

Written by Nikki Gordon-Bloomfield, this article originally appeared on All Cars Electric, one of VentureBeat’s editorial partners.

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