AUDI has unveiled its concept rival to BMW's MINI.

Its metroproject quattro design study, revealed at the Tokyo Motor Show, measures less than four metres and provides clues to the look and packaging of a future Audi sub-compact production car.

Power is provided by a modified version of the 1.4-litre Turbo FSI petrol engine recently adopted by the A3, combined with a lithium-ion battery-powered electric motor mounted behind the rear seats, which reduces fuel consumption and emissions by around 15 per cent.

The petrol engine's increased 150bhp output, up from 125bhp in the A3, is delivered at 5,500rpm, and its 40Nm higher torque output of 240Nm peaks from just 1,600rpm.

The electric motor adds 41bhp and an extra 200Nm of torque, and when engine and motor work in unison the metroproject quattro is able to accelerate from rest to 62mph in 7.8 seconds and reach a top speed of 124mph.

A combined economy figure of 57.6mpg is possible, coupled with modest C02 output of 112g/km.

The metroproject quattro is able to derive its power solely from its petrol engine, purely from its electric motor or through a combination of the two.

If the driver opts for electric operation alone - a particular advantage for urban driving and shorter distances - the metroproject quattro is able to cover up to 62 miles at speeds of up to 62mph, silently and completely cleanly, before its lithium-ion batteries need to be "refuelled" by a power socket. Energy released during braking is transformed back into electrical energy rather than being released as heat and wasted, helping to conserve resources even more effectively.

While only the petrol engine is running, the metroproject quattro sends drive through its front wheels, and while powered by the electric motor on the back axle alone it is effectively rear-wheel-driven.

When the two operate simultaneously, the compact Audi is able to offer four-wheel-drive.

The metroproject quattro also features the Audi magnetic ride adaptive damping technology, which has won plenty of praise already in the TT and R8 sports cars, and drive select system introduced recently in the all-new A4 Saloon.

The highlight of the cabin is the removable hand-held Audi mobile device, which not only offers mobile telephony, GPS navigation and audio and video playback, but also serves as the control unit which can be set and adjusted from outside the car. The driver can enter destinations into the satellite navigation unit, programme the audio system or switch on the heating from the comfort of an armchair at home before setting off.