Electric BMW i3 may spawn i5 family car

German carmaker BMW is intent on making electric cars desirable with their little i3 city vehicle and sexy i8 sports car. The problem with both of those is that no matter how much a family desires them, neither model can practically do duty for the usual family chores of lugging people, gear and groceries.

However a solution may be in the works, with BMW planning to stretch the i3's platform to build a new vehicle, tipped to be called the i5 according to UK website Autocar.

Their report suggests the little car's 4000mm could be extended by just another 100mm of leg room in the back and another 150mm of rear overhang for extra cargo, to create a family-friendly electric package longer than the current Mini Countryman -- although the next Countryman is likely to be bigger than that as well.

The i3's carbon-composite body is built onto a separate aluminium chassis 'skateboard' rather than integrated into the monocoque steel platform of a conventional vehicle, so stretching will be a simpler task involving extending the platform length -- and changing the design of the rear doors.

But it could also mean the necessity of muscling up the drivetrain to cope with the extra load without penalising range. The i3 has a 130-160km range when powered entirely by the  lithium-ion battery pack feeding a 125kW/250Nm electric motor. And while the range is boosted to 300km by adding the optional 647cc rear-mounted motorcycle engine -- which tops up the battery charging but also adds 150kg of weight to the i3.

Also watch: BMW i3 electric car video review

We've reported previously that BMW could build a range of body designs on the same rolling electric platform. And with the brand tipped to have already registered nameplates ranging from i1 up to i11, a volume-targeting family car is the next logical step for the birth of a new BMW sub-brand.

This reporter is on Twitter: @KarlaPincott