This is the first picture of the new Oxford-built electric Mini.

Full details of the ground-breaking car have been unveiled by BMW, with the models already in production at Cowley.

A test run of 500 vehicles — known as the Mini E — will take to the roads in the United States next month, as part of an extended programme to explore the possibilities of electric power.

BMW said the move to electric power — first revealed by the Oxford Mail in July — was designed to cut fuel consumption and harmful emissions produced by conventional vehicles, particularly in big cities.

Spokesman Dan Connell said: "This is an advanced testing programme and the technology may end up in a Mini, or a BMW, or a new brand of vehicle altogether.

"There are still several years of development to take place, but the Mini bodyshell lends itself very well to the development."

The cars will have a range of about 150 miles powered by a battery, which can be fully charged in two-and-a-half hours using a specially-developed plug-in box.

Unlike electric vehicles of the past, the Mini will be quick off the mark and will be able to reach 62 mph in just 8.5 seconds.

The body shells are being built in Cowley and then taken to a BMW factory in Munich, Germany, where the battery, electronics and transmission will be added. They will then be shipped to the States where they will be tested by private and corporate customers who will lease them for a year.

The car will be officially launched at the Los Angeles Auto Show next month. All the cars will be painted silver, with bright yellow power plug logos.

Full-scale production of electric Minis is not expected for several years.