A future entry level Audi pitched under the A3 was hinted at by the company's new sub-compact metroproject quattro concept revealed at the Tokyo Motor Show.

Audi itself said that the the metroproject quattro could provide clues to the look and packaging of a future Audi sub-compact production car. 

Power for the Vorsprung durch Technik study 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 150PS output, up from 125PS 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 41PS 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.

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, their interplay controlled by the on-board management system.

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 all the advantages in composure and control that four-wheel-drive brings.

Audi said that more enthusiastic driving, which would call the two power sources into play simultaneously, is enhanced by a sophisticated McPherson strut front and four-link rear suspension configuration, electromechanical speed-sensitive power steering with a low energy draw and Audi magnetic ride adaptive damping technology, already employed in the TT and R8 sports cars.

The metroproject quattro's transverse 'east-west' engine installation, short overhangs and similarity in height to the larger A3 hatchback maximise interior space.