The BMW i3 is a compact Ev with petrol range extender. On the battery alone you get up to 160km. For longer distances the range extender allows for up to 340km of range.
The Range Extender (REx) is a small, very smooth-running and quiet combustion engine which runs on normal petrol. This motor drives a generator which in turn charges the high-voltage battery so that the vehicle can continue to drive electrically.
The vehicle is a excellent for round town and longer distance journeys.
(Information sourced from: http://www.bmw.co.nz/en/all-models/bmw-i/i3/2013/drive.html#range-extender)