BMW has made a point of incorporating a great deal of new technology, such as the wide use of lightweight carbon fiber, into its vehicles. But it has borrowed a concept from General Motors so the i3 will also be available in an “extended range” version similar to the Chevrolet Volt.
If desired, the BMW i3 is also available with a range-extender engine, which maintains the charge of the lithium-ion battery at a constant level while on the move as soon as it dips below a certain value. Performing this role is a 650cc two-cylinder, 34-horsepower engine, which is mounted immediately adjacent to the electric motor above the rear axle, BMW said.
Maximum range stands at approximately 186 miles, which is more than double the range of battery electric version of the i3.
“The BMW i3 is the world’s first electrically powered car with a range-extender engine used exclusively to generate electric power,” BMW said. The range is limited by the size of fuel tank, which can only car nine liters, or nearly 2.5 gallons, of gasoline.
BMW designers also said the range extender has no effect on luggage capacity since the fuel tank is located in the front section of the car.
The i3 body structure – shaped by its LifeDrive architecture developed for the i3 – enables the use of a trailing edge element made by glass-fiber-reinforced plastic injection molding.
The direct connection between the power electronics and electric motor in the rear of the BMW i3 reduces the length of cabling required and cuts the overall weight of the drivetrain by around 1.5 kilograms.
Other elements of the i3’s construction also adapt new technology to BMW’s goal of sustainable mobility.
Construction techniques aimed at reducing weight also set the tone for the chassis components of the BMW i3. For example, the forged aluminum suspension links weigh around 15% less than in a conventional design, the hollow drive shaft is 18% lighter than a conventional equivalent, and the standard 19-inch forged aluminum wheels of the BMW i3 are 36% lower in weight than comparable steel rims of the same size.
Using a magnesium supporting structure for the instrument panel saves weight on two fronts. Superior material attributes over conventional sheet steel allow these components to boast optimized geometry, which results in a weight reduction of some 20%.
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The magnesium structure also strengthens it, allowing a reduction in components and lowering weight by another 10%.
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The door trim panels are made from renewable raw materials and tip the scales around 10% lighter than conventional equivalents. And the rigorous application of the lightweight design strategy extends to screws and bolts made from aluminum.
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