Volkswagen believes electric drive will be the future and is launching real world tests of its Twin Drive plug-in hybrid Golf in Berlin with twenty vehicles.

The system differs from other hybrids. It can use either a diesel or petrol engine and both the engine and electric motor are linked to a single gear transmission.

It uses electric-only power from 0-50 kph at which point the combustion engine takes over with the gearbox set in 5th gear. Reverse is always under electric power.

Development so far has been carried out using a 1.5-litre TDI engine and VW is claiming fuel consumption of 2.5l/100km - about 113 mpg - and eight kilowatt hours of electricity over a typical 100km commute in and out of Berlin.

VW is specifying that for the Berlin tests, the plug-in charging of the electric motors will be from electricity generated from renewable sources provided by electricity company E.ON. Currently 13 per cent of Germany's electricity is generated by wind power and this is expected to rise to 30 per cent by 2020.