Big crowds have gathered for the unveiling of Audi’s Sportback concept car in a stormy Detroit.

The four-door Sportback concept is expected to be badged Audi A7 when it arrives in showrooms in a couple of years.

And if Audi’s past concept cars are anything to go by the production car will look almost identical to the Detroit show car when it goes on sale.

The German manufacturer wants to build on the success of the Audi A3 Sportback, which is out-selling the standard model.

The Audi A3 Sportback is essentially a stretched hatchback, with more legroom for rear passengers and a bigger boot than the standard model.

In Audi A7 guise this translates to a stretched coupe silhouette, with quarter light rear side windows.

The nose sticks to modern Audi design, with a large grille and aggressive LED headlights.

A panoramic sunroof and light wood cockpit trim hint towards a departure from the dark materials used in recent Audi models, but it’s not known if they will make production at this stage.

Despite being a big car (4.95 metres long) the A7 is expected to achieve more than 40mpg, thanks to a 3-litre V6 TDI engine tuned for optimum economy as well as power.

Expect 0-62mph in less than seven seconds and around 156g/km of carbon dioxide emissions. A year’s road tax should cost around £150.

The concept car has carbon ceramic brakes - offering supercar levels of braking power – but we probably won’t see them fitted to a production A7; unless Audi builds a hot RS7 version.

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