AUDI'S wolf in sheep's clothing - an estate car with a top speed of more than 170mph - is back in business.

The German car maker has announced it will be launching a new version of the mighty RS4 Avant later in the year.

Powered by a 450ps 4.2-litre naturally aspirated V8, the super hot Avant is capable of 0 to 60mph in 4.7 seconds and can hit 174mph with an optional power upgrade in place.

In ‘regular' form its top speed is electrically restricted to 155mph.

Audi says it expects the car to be on the streets late in September and although no pricing has been announced, expect it to be well beyond £50,000.

The RS4 will be available only in the Avant estate body style but has subtle body tweaks such as flared wheel arches. It is also slightly longer, wider and lower than a standard A4 Avant.

The engine is the same as that Audi uses in the RS5 coupe and despite the awesome performance it is rated as averaging 25.7mpg.

With quattro all-wheel-drive the new RS4 will also have the option of coming with a dynamic ride control system for improved handling.

There is even a device which varies its steering ratio by nearly 100 per cent depending on speed and automatically countersteers slightly at the cornering limit for even more precision and stability.

In true German sports car tradition the interior is predominantly black with carbon inlays as standard.

The high performance RS4 Avant has become an Audi classic since the original was introduced in 2000 and the new model is the quickest yet. The previous model was last produced in 2008.