Bentley say the car being driven by Oxford driver Andy Wallace at this weekend's Le Mans 24 Hour race will be one of the most advanced on the circuit.

Team Bentley will field two 600 horsepower EXP Speed 8s - the only fully-enclosed prototype cars entered - which are built around three hoops of carbon fibre.

The largest of the trio surrounds the car behind the driver, the smallest goes around the pedal box, while the third central hoop encircles the car's structure roughly around the driver's knees.

This forms the platform on which the stressed carbon-fibre body is attached, to create a structure that is exceptionally strong, stiff and light.

Bentley said its twin-turbo 3.6-litre V8 is allowed to use an air restrictor one millimetre larger than those on cars in the open class, which will give it a power advantage.

The EXP Speed 8 is also extremely light. Despite the extra weight of the windscreen, roof and doors that its closed configuration demands, it will still have to carry ballast to make sure it tips the scales at the 900 kilograms required for Le Mans prototypes.

Audi will be looking to repeat its dominant 1-2-3 result of last year with ex-F1 driver Johnny Herbert flying the flag for Britain in a "privateer" 220mph Audi R8.

Meanwhile, MG are making an historic return to Le Mans.

The year 1965 marked the last time an MG competed in the 24-hour Le Mans race. Paddy Hopkirk and Andrew Hedges finished 11th in the race - the best an MGB had achieved there and second in its class.

Sporting the vivid green MG octagon on X-Power grey paintwork, the new MG Lola EX257 sports car has been produced by Lola Cars International to compete in the LMP 675 class at Le Mans.

Advanced Engine Research (AER), responsible for the power unit Lola used to win last year's LMP 675 class at Le Mans, was commissioned to produce a new lightweight 2.0-litre turbocharged four-cylinder engine.

Mark Blundell, who is a former Le Mans winner and experienced Formula 1 driver, said: "It's great to be returning to Le Mans and it's fantastic to go with five other British drivers in the team."

The MG team includes Oxford-based Scot Anthony Reid, Jonny Kane, Warren Hughes, Kevin McGarrity and Julian Bailey.

*Toyota Formula 1 test driver Allan McNish will be at the Le Mans 24 Hours - but not as a competitor.

The 31-year-old from Dumfries, in Scotland, will be working as a commentator for an American satellite TV station.