What material forms the passenger cell of the BMW i3, helping make it unusually light?

The BMW i3 uses a carbon-fiber-reinforced plastic passenger cell to reduce weight. BMW called this structure the Life module, while the separate aluminium chassis carrying the drivetrain and suspension was the Drive module.

The i3 entered production in 2013 and was notable because carbon-fiber-reinforced plastic, or CFRP, was used extensively in a mass-produced electric car rather than only in small quantities in specialist vehicles. Lower mass helps an electric vehicle use less energy and can partly offset the weight of its battery.

The i3’s exterior body panels were mainly made from lightweight plastic, so the answer is not simply “plastic.” Nor is the entire vehicle made from carbon fibre: its underbody and other components use aluminium and steel. The i3 also offered an optional range-extending petrol engine in some markets, but that did not change the material used for its passenger cell.