THEY'RE calling it a paradox of practicality and extremity.

Apt description, no doubt, for the Audi's latest high performance holdall the RS4 Avant.

The V8-powered super estate, now in its third generation, will cost £54,925 when it sizzles onto UK streets in the autumn.

Under the bonnet is a 4.2-litre engine producing a hefty 450PS and capable of propelling the Avant to 62mph in a fleeting 4.7 seconds via the standard S tronic transmission.

And a governed top speed of 155mph can be increased to 174mph if required, all with the potential for returning up to 26.4mpg according to the Combined cycle test.

In common with every Audi RS model, the RS 4 Avant features quattro permanent all-wheel drive, bolstered in this case by the advanced crown-gear centre differential and sports rear diff for smooth torque transfer.

A 40:60 split operates in normal conditions, but up to 70 per cent of power can be channeled to the front wheels and as much as 85 per cent to the rear ones depending on the conditions.

There's also a torque vectoring system, which acts on all four wheels, and Electronic Stability Control with Sport mode.

The RS 4 Avant looks the part too with its polished 19-inch aluminium wheels and lowered body.

Dynamic Ride Control and dynamic steering options are available individually or combined as part of a new £2,250 Sport Package, which also includes larger 20-inch rotor design aluminium or titanium-look alloy wheels plus a sports exhaust system.

The interior of the car is finished completely in black, with the exception of the roof lining, which is optionally available in Moon Silver, while there are also chrome clasps and carbon inlays.

Standard kit includes DVD-based sat-nav, Bluetooth mobile phone preparation, cruise control and Audi Music Interface iPod connection.

Options for the luggage compartment, which offers up to 1,430 litres of cargo space, include a rail system with load securing net and a power-operated tailgate.