Opel’s stunning Flexstream concept car - not for production - demonstrates shows that cars that run on batteries don’t have to be small and boxy. It shows how large family saloons could look in the future.

Flextream is based on the same drive system as the ‘extended-range’ Chevrolet Volt and Opel-Vauxhall Ampera models due on sale over the next couple of years. It is powered by battery until the charge runs out at which point a 1.4-litre EcoTec petrol engine cuts in to effectively act as a generator to keep the electric motor running.

Boris Jacob, who heads up General Motors Europe’s advanced design team, said: “Flexstream is our take on premium car which is just as environmentally friendly as the Ampera.

“Although it has a very sporty look we have gone for a full four-seater and used the same flex doors from the new Meriva. The concept has many design themes that will be introduced on future Opel and Vauxhall models.”

These include the 'tick' shape being introduced around the headlamp design on the company’s current models.

Jacob said: “We have taken that and designed a complete head and tail lamp in the shape of the tick. The C-pillar design which reduces drag will also be introduced on our future vehicles.”

Gherado Corsini, than man in charge of introducing GM’s electric vehicles into Europe, said that Ampera is on track for its European launch next year – although there is still no decision on where it will be built.

Vauxhall holds high hopes that it can win the competition from the company’s other European plants and build the Ampera at its Ellesmere Port factory.

Corsini said that was undecided but indicated GM was impressed by recently announced incentives for environment-friendly vehicles by the British government.

He added: “These will certainly help ramp up volumes faster while the mayor of London has also committed to making the city the European capital for environmental vehicles.”

Corsini said that, in recent European trials, the Ampera had reached its range targets, running 60km (about 35 miles) on a single battery charge and a total of 700km (440 miles) with a tank of petrol .

He also addressed concerns over the used values of electric vehicles.

CAP, the company that specialises in forecasting residual values in the UK, said there are issues over battery life, finance and replacement costs as well as charging systems and overall running cost which make predictions impossible.

It said that that battery replacement costs threaten to render commercial electric vehicles, in particular, worthless after warranties expire.  Contract hire or leasing operators and funders will also need substantially more information before they understand their risk position.

Corsini said: “We are working on a number of business models which include residual values. We are making sure, for example, that major components such as the electric motor and battery last 10 years and this will be reflected in our warranty.”

In terms of future environment-friendly vehicles, Corsini said: “We have the Flextreme which shows how our technology works in multiple vehicles. We have also previously showcased a premium model, the Cadillac Converj

“We are also close to introducing fuel cell technology although the issue with this remains the hydrogen infrastructure. Like the petrol engine we use in Ampera, the fuel cell is just a different way of extending the range and Ampera has been designed with fuel cells in mind.”