London to Edinburgh for £8.50 in the VW 'tandem' (just don't bank on bringing too much luggage

But this is a vehicle of the future: Streamlined, lightweight  -  and capable of an astonishing 282 miles per gallon.

That, say its makers, means it is the most economical road car in the world.

Volkswagen's One Litre car could change the way we drive

Called the One-Litre, because that's how much fuel it needs to travel 100km, it is still just a prototype. But Volkswagen hopes to have it on the market as a limited edition from 2010.

The two-seater runs on diesel and the tank holds just 1.4 gallons (6.5 litres). But it is so fuel efficient that a full tank could last you for more than 400 miles.

You could drive from London to Edinburgh without refuelling and still have 70 miles
worth of fuel to spare.

Based on the current average price of diesel of £6 a gallon (131.9p a litre), it would cost just £8.50 to fill up the One-Litre.

Its efficiency is helped by its aerodynamic design. Shaped like a teardrop, it has tandem seats like a jet fighter with the passenger sitting behind the driver, a gull-wing door and sheathed wheels.

Even wing mirrors have been dispensed with. Cameras and electric displays help the driver to see what's behind from his cockpit-like seat.

It could cost up to £23,000 to buy, with a top speed of 75mph, but you won't be able to pack a lot in  -  the storage space behind the seats measures just 2.8 cubic feet.

The car is made of carbon fibre composites and uses one single cylinder 0.33 litre engine.

The magnesium steering wheel adds just one pound and, to keep it as light as possible, it is not even painted, so potential buyers are likely to have to settle for the default black.

It is also a 'smart' car: The engine turns off when the car is stopped at lights and automatically restarts when the accelerator is pressed.