Detroit show: Audi RS7 Sportback blasts in

AUDI has unleashed the hardcore RS7 Sportback, its twin-turbo V8-powered rival for the BMW M6 Gran Coupe and Mercedes-Benz CLS 63 AMG.

The hottest version of Audi’s niche five-door A7 coupe was revealed overnight at the Detroit motor show, emerging hot on the heels of the third-generation RS6 Avant revealed overseas last month.

First Australian deliveries of the RS7 Sportback will hit showrooms in early 2014, where it will join the RS6 Avant (set for launch in late 2013), RS4 Avant (due early 2013) and RS5 coupe (already on sale).

Local pricing will not be revealed until closer to launch, but the RS7 will supplant the limited-edition and comparatively tame S7 (priced from $179,900) as the range flagship.

As with the new RS6 wagon, power for the RS7 Sportback comes from a twin-turbo 4.0-litre TFSI V8 engine producing 412kW between 5700 and 6700rpm, with 700Nm of torque from just 1750rpm, driving through all four wheels via Audi’s 60:40 rear-biased quattro all-wheel-drive system.

This is some 103kW and 150Nm more than the lower-tuned version of the same engine used in the S7 Sportback.

The RS7 matches its load-lugging RS6 sibling for speed with its claimed zero-to-100km/h sprint time of just 3.9 seconds – three-tenths faster than the rear-drive BMW M6 Gran Coupe and updated Mercedes-Benz CLS 63 AMG, both of which also premiered in Detroit this year.

The RS7’s sprint time equals Porsche’s flagship Panamera turbo, but neither match Mercedes’ special 430kW/800Nm S-Model CLS, which takes the cake with a time of just 3.6 seconds.

Top speed for the RS7 is electronically limited to 250km/h, but can be stretched to 305km/h for extra cost as part of a “dynamic plus” packageThe high-revving V8 engine – which features a pair of twin-scroll turbochargers – consumes a low 9.8 litres of fuel per 100km/h on the combined cycle.

Fuel-saving features include idle-stop, electromechanical steering and cylinder deactivation – the latter of which runs the car on four cylinders at low to medium engine speeds.

Audi’s TFSI engine is matched exclusively to an eight-speed tiptronic automatic transmission with paddle shifters and a shift light. Audi says the lower ratios are closely spaced for swifter response, but eighth is geared tall for high-speed cruising.

The RS7 sits on adaptive air suspension that can lower the body in its sportiest setting by up to 20mm, and features torque vectoring that brakes the inside wheel, negating understeer.

The stability control can be completely disengaged for track use.

Audi also offers firmer steel springs and three-stage adjustable dampers as part of an options package called “sports suspension plus with dynamic ride control”.

Standard 20-inch forged lightweight wheels can be replaced with optional 21-inch wheels in a choice of three designs.

Behind all four wheels sit ventilated disc brakes, measuring 390mm at the front, but Audi also offers mammoth 420mm carbon-fibre ceramic discs with anthracite grey calipers as an option.

The German brand has not revealed the RS7’s kerb weight, but says the body contains up to 20 per cent aluminium, and a large proportion of lightweight high-tensile steels.

Styling upgrades beyond the monster rims are subtle, but include new black honeycomb grille inserts, a larger front air dam, more matte aluminium body highlights, a new rear diffuser and bolder elliptical twin tail-pipes.

Likewise, the plush cabin from the regular A7 remains largely unchanged, though Audi has added new black instruments with white scales and red dials, a 3D RS7 logo in the tachometer, more aluminium trim and chunkier leather/Alcantara sports seats.

RS7 badges also adorn the flat-bottomed steering wheel, key, door sills and multimedia system.