BMW i3 Range Extender (REX)

With a range of 130-160 kilometers in the standard COMFORT driving mode, the BMW i3 largely covers the majority of driving demands for a typical commuter driving style. If a regular use of the BMW i3 on longer distances is desired, an optional Range Extender (REx) for the BMW i3 makes an increase of the range to approx. 240-300 km possible, and with especially efficient driving even up to 340 km. The range extender REx is a small, very smooth-running and quiet combustion engine which runs on normal gasoline. This motor drives a generator which in turn charges the high-voltage battery so that the vehicle can continue to drive electrically.
Quelle: BMWi Kanal