The four-cylinder only intervenes when you floor the accelerator. You really have to look at the gauges to see if it is running on petrol or electricity at steady speeds. According to BMW you should be able to drive emission-free for 51 kilometres (NEDC), but in practice you can count on about 40 kilometres.
The battery can be charged at a maximum of 3.7kW, requiring three to four hours to fully charge at a wallbox or a public charger. During our test, we consumed an average of 3.7L/100km of petrol and 20.3kWh/100km of electricity. Very respectable values that can, however, turn out lower or higher as they depend entirely on your charging and driving behaviour.