In the battle of super-estate Top Trumps, Audi has just nicked the goalposts – in a suitably commodious family wagon. Despite boasting two fewer cylinders and 1200cc less than the old V10 RS6, the new RS6 Avant is even faster over the 0-62mph sprint, and will top out at over 190mph.

Wow! A family estate that can out-accelerate a Porsche 911 Carrera?

Forget Carreras: this thing will give 911 Turbo owners the sweats at the traffic lights. It's all thanks to a brawny-yet-brainy 552bhp and 516lb ft bi-turbo 4.0-litre V8. The twin-blowers and intercooler nestle inside the engine's 'vee', for compact packaging and less 'lag', and it shuts down one cylinder bank under light loads to save fuel. Although the motor shares much with the V8 found in the Bentley Continental GT, Audi has equipped its ballistic A6 with RS-model specific mapping for improved engine response, and a throatier soundtrack.

Despite the downsizing from the old car's Lamborghini-derived 5.2-litre V10, the new RS6 will hit 62mph in 3.9sec (old car: 4.6sec) and run into the limiter at 155mph. Opt for the Dynamic pack and that jumps to 174mph; pay even more for Dynamic Plus and you'll canter on to 190mph.

So, how can a car 20bhp down on the old RS6 Avant be so quick?

The new RS6 Avant weighs around 100kg less than its predecessor – which tipped the scales at an obscene 2025kg – thanks to its smaller engine and the part-aluminium structure of the latest A6. Less weight and maximum torque from just 1750rpm should make the RS6 Avant a true supercar-baiter.

The addition of a fast-shifting eight-speed automatic also helps toward that headline acceleration figure, and to keep the fuel consumption down. Audi claims the new RS6 Avant is a massive 40% more fuel efficient than the old car, but given that's comparing it to a car whose fuel gauge emptied like the tank was a colander, the new one's still not going to make the company car list. The official figure is 28.8mpg, 0.3mpg better than the identically powerful (and nearly as hefty) BMW M5.

What other hardware mods are fitted to the RS6?

There's an active exhaust system, which opens flaps under full throttle to unleash more noise, and that can be further upgraded by speccing the optional sports exhaust. Also on-board is unique-to-the RS6 air suspension. This stiffens the dampers in the sportier driving modes, and can lower the car's ride height by 20mm.

Braking duties are entrusted to rose petal-outline vented discs which save unsprung weight, like on the RS4 Avant. The standard front stoppers are steel 390mm items, grabbed by six-pot calipers. Not big enough? An expensive delve into the options can offer huge 420mm carbon ceramic discs.

Run me through the RS6 Avant's visual modifications

Up front you'll spot the deeper front grilles, framing a retro 'Quattro' logo. Blistered wheelarches accomodate 20-inch forged wheels as standard, or 21-inch cast items as an option, in silver or black. At the rear, this mad-as-a-hatter estate gets RS-trademark oval tailpipes, a small diffuser, and subtle roof spoiler.

Inside, the top-spec RS6 features sports seats, carbonfibre inlays and alloy detailing for the pedals and switches. There's also a shift-up light to compliment the white dials, and a new display offering boost pressure, oil temperature and gear selection.

The Audi RS6 Avant sounds like quite a recipe. When can I buy one?

If you're keen to haul 1680 litres of cargo at near-Ferrari pace, first sales should kick off in the summer of 2013, with prices expected to hover around the £75,000-£80,0000 mark. The RS6 Avant's only direct rival is the Mercedes E63 AMG Estate: BMW's M5 and Jaguar's XFR-S are strictly saloon only.

And don't get caught out waiting for a saloon RS6: CAR understands that model wont't see the light of day. It'll be shunned in favour of the sleeker RS7 Sportback four-door coupe, sharing the same 552bhp powertrain.