BMW i3 Range Extender

BMW i3 Range Extender

Small Family Cars

1. BMW i3

Model/Engine size:
BMW i3 Range Extender
Fuel economy combined:
470 mpg* see text
BMW i3 Range Extender


The BMW i3 uses revolutionary materials, including the first ever application of Carbon Fibre Reinforced Plastic (CFRP), to create an electric car that is lighter than a 1 Series but has as much interior space as a 3 Series. It is ground breaking and you can read what we think about it here. In this summary we’re going to explain what the range extender option adds (or detracts) from the party.

The range extended market is in its infancy, and very different approaches are starting to emerge. Generally the concept is to provide a usable electric range but then have a back-up petrol or diesel engine which can be used to make electricity on board the car (there is no mechanical connection to the wheels), so there is no issue with ever being stuck at the side of the road if you run out of electricity, and opening up the possibility to buy an electric car even if you regularly exceed the daily electric range.

In the case of the i3, BMW has taken this concept to the extreme. Yes it has a petrol engine, but the fuel tank only holds 2 gallons (9 litres). This is because BMW doesn’t want you to drive the i3 on petrol all the time, rather it is an emergency back up that guarantees you won’t get stranded. The petrol engine in question is a tiny 650cc two-cylinder unit which, like the fuel tank, has been designed to squeeze into the platform without compromising the electric range.

To reiterate the ‘occasional’ nature of the petrol back up, the tank only gives you an extra 75 – 93 miles of petrol range which you might notice means that if you drive an i3 in petrol mode you will not be getting 470 mpg but rather a very underwhelming 40 or so mpg which is over 160g/km CO2. The slight weight gain also means that the real world electric range is reduced from 81 – 100 miles for the pure electric model to 75 – 93 miles.

So the range extender i3 is more expensive to buy, less efficient, slower, heavier, more expensive to run and has a petrol engine that you aren’t really supposed to use. If you want an i3 but regularly travel just further than its electric range it could make sense, but if you were hoping that the i3 would be efficient in petrol or electric mode and would allow you to replace a conventional car for regular long journeys, you will be disappointed.


Read our full BMW i3 review

Official electricity consumption: 115 Wh/km* underestimated by test actually approx 140 Wh/km
Battery pack: 22 kWh lithium ion pack (18.8 kWh usable)
Recharge time: 240V charge 8 hours; 32A fast charge 3-4 hours; Rapid DC 50 kW charge 30 mins 0-80%

Please note that CO2 emissions quoted for electric cars are not directly comparable to diesel and petrol cars. This is because CO2 emissions quoted are calculated by Beating Spirit and include the emissions created at the power station turning fuel (e.g. gas etc) into electricity and in transmitting and distributing the electricity to an end user. They do not include the actual production of the fuel (e.g. gas extraction and refinery emissions). Petrol and diesel emissions are supplied by car manufacturers and are based solely on the fuel burnt in the engine (tailpipe emissions) and do not include the production of the fuel or distribution to a fuel station. In practice this means that electric car emissions are over estimated relative to petrol and diesel. For instance if an electric car, a petrol car, and a diesel car are all reported to emit 100 g/km CO2, the electric car actually has lower emissions.


Fuel economy, extra urban:
Fuel economy, urban:
CO2 emissions:
Officially 13 g/km* see text. Estimated 75 g/km electric (average UK electricity) over 160 g/km petrol mode g/km
Green rating:
VED band A - £0 a year
1390 kg Kg
Company car tax liability ( 2015/16 ):
£34,130 (Qualifies for £5,000 Government grant)
Insurance group:
170 bhp
Max speed:
93 mph
7.9 seconds
Euro 6: