Audi Sportback concept

So what do you think?

This Audi Sportback concept car has been unveiled at Detroit to gauge public reaction to what would be a Mercedes CLS and VW Passat CC rival.

However, your opinions are only likely to shape smaller details on the four-door car, as it is already said to be certain to go into production in late 2010.

The car would be called the Audi A7 and plans are said to be so advanced that Audi is also thought to be preparing a four-door A7 convertible and a diesel-electric hybrid. A 2011 on-sale date is being mooted for these cars.

The concept car is powered by a 222bhp 3.0-litre V6 diesel engine capable of 47.9mpg. It produces and 406lbft of pulling power, a top speed of 152mph and a 0-62mpg time of under seven seconds.

It is also linked to a stop-start system, which insiders will start appearing on four cylinder-engined production cars later this year, and then on cars fitted with V-angled engines and cars equipped with semi-automatic gearboxes shortly afterwards.

The Sportback concept also uses a seven-speed S-tronic gearbox, regenerative braking and low rolling resistance tyres to improve fuel efficiency.

It also has Continuous Damping Control, as available on the Audi Q7, to improve the ride quality without compromising body control, and carbon ceramic brakes, which aid stopping power but are likely to be too expensive to make production.

Audi also says the Sportback design style will feature extensively in new models, following the success of the Audi A3 Sportback. An Audi A1 Sportback is rumoured to be under production.