The proof was put on show for the Japanese, a nation that is keenly aware of the need for 'eco' cars. VW engineers are hoping to get the green light to put the model into production.

The EcoRacer was a huge hit with viewers when VW revealed astonishing figures . . . 83mpg and 143mph in the same breath. So goodbye to the old notion that top fuel performance and low running costs must mean slow starts and easy-throttle hybrid technology.

The EcoRacer is a two-seater coupe with materials and design features which will be in lightweight cars of the future.

Bodywork and chassis are made of carbon fibre reinforced plastic which is rust proof, strong and, most importantly, recyclable. At present it is much more expensive than steel, so for the moment this science is suitable only for small-volume cars.

Surprisingly the styling is very ordinary up front . . . big mesh grille and twin-stacked headlights. But it gets better. Over the mid-mounted engine is a T-bar roof that can be removed and stored behind the seats, turning the EcoRacer into a roadster.

Also the top of the dashboard and windscreen can also be swapped for a much smaller wrap-around mini screen . . .

a good idea for less air resistance.

But it is diesel power that makes this coupe/racer/roadster so powerful and economical. The 1.5 litre turbo-charged unit puts out 134bhp and a heavyweight punch of 249mm of torque to the rear wheels. The materials and engineering used are secret but VW says we can expect to have this type of material and technology in family saloons within the next five to six years.

Design features include a flip-up roof for easy entry. But once inside, the lightweight design means a cockpit sparsely furnished apart from the bucket seats.

The furniture, what little there is of it, is of course carbon fibre.

Even the dash cluster is high tech. For normal driving the read-outs are for water tempt, fuel range and speed. But select 'race mode' and these automatically change to engine revs, turbo-boost and oil temperature. VW have created a stylish environmentally-friendly car for the future.

Roll on eco-power at this level.