What is it?

The most powerful series production Audi ever. With 572bhp, the new second-generation RS6’s twin-turbocharged 5.0-litre V10 engine provides it with a whopping 99bhp more than the German car-maker’s previous top gun, the 473bhp twin-turbo V8-powered first generation RS6.

This new four-wheel drive mega-estate is also the fastest accelerating road car to ever head out of Ingolstadt. Officially, it takes just 4.6sec to go from zero to 62mph, placing it on the same performance plane as Audi's mid-engined R8. Less than ten seconds later, though, RS6 owners will be hauling past the 124mph mark at a rate that grants their car a passport into a club of truly exotic supercars.

Speed, like all high-end Audi models, is limited to 155mph, though Audi invites owners to extend it to 174mph as part of a sports package that adds a remapped ECU among other goodies. Not enough? The new car’s development boss, Stephan Reil, says he’s seen 205mph during prototype testing on a deserted autobahn in Germany.

For all the headline-grabbing value of these performance figures, though, it is the RS6’s deep reserves of torque that really shape its on-road character. With 479lb ft spread from 1500rpm to 6250rpm, the big Audi takes off like a space rocket from idle all the way up to its 6800rpm redline.

The car's new four-valve-per-cylinder engine is derived from the naturally aspirated 5204cc unit found in the S6. Both share the same 90mm cylinder bore centre spacing and 84.5mm bore measurement, but the big news is the appearance of two turbochargers. Running a conservative 0.7 bar of boost pressure, they swell specific output to 115bhp-per-litre.

The only gearbox on offer is a six-speed automatic, operated by remote shift paddles on the steering wheel, and offering the choice between three distinct shift modes – automatic, sport and manual.

At 2025kg, the RS6 takes some stopping and, typically, Audi has left nothing to chance. The standard brakes combine 390mm (front) and 356mm (rear) steel discs with eight-piston (front) and single piston (rear) callipers.

Initially, the new Audi RS6 will be built in Avant form only, though a 60kg lighter saloon version, promising even sharper performance, will head into UK showrooms this coming autumn.

What’s it like?

Sensationally quick. Nailing the throttle leaves you in little doubt that the RS6 is the new autobahn performance king. Given enough space, it shrinks distance in a way no other car with seating for five adults and 565-litres of luggage space can.

With all that under-bonnet firepower and a set of closely stacked gear ratios to deploy it, the new Audi makes long straights seem short and fast constant-radius bends suddenly much tighter than they first appeared. Immense thrust - the sort that momentarily pins you in the seat - is always just a twitch of the right foot away.

The only real concern we have relates to the RS6's rather lumpy ride. Final conclusions will have to wait until we have the chance to drive it in the UK, but in a bid to maintain body control the suspension has been given a heavy reworking, with spring rates increasing by 12 per cent over the already-harsh-riding S6.

Audi has also fitted the car with adaptive dampers offering the choice between comfort, dynamic and sports modes. The comfort and dynamic settings cover most bases well, but the overly firm sport setting is really only suitable for track work.

For all its undoubted motorway strengths, though, the RS6 cannot defy the laws of physics. This is a big and heavy car, and it takes plenty of road space for the driver to feel entirely confident about operating near its limits.

At 2.2 turns lock-to-lock, the steering is pleasingly direct but not exactly generous in feedback. Good news, though: Audi has managed to make its responses more linear and much better weighted than the old RS6's. The old car’s tendency to tramline heavily under braking has also been greatly improved upon, making this new one more controlled and fluid in its actions over challenging back roads.

As with all recent models from Audi’s quattro GmbH division, the RS6's four-wheel drive system doles out the drive in a 40:60 split front to rear. This car flatters its driver when the road turns twisty, allowing you to feed in huge amounts of power early and carry great speed into corners without fear of some nasty tail-led reprisal as you begin to wind on lock.

There’s tremendous neutrality in the way this car attacks bends, while grip is predictably massive. Once those high levels of adhesion have been breached, the onset of electronic stability control fades in progressive and well-contained understeer.

As a point of reference at just how much the RS6’s dynamics have been improved, Reil claims the new model is capable of lapping the Nurburgring a whopping 20sec faster than its predecessor. “We spent a lot of time running at the Nordschliefe,” he says. “Conditions vary and every lap you run is unique, but we managed to get down to 8min 09sec during our final tests there.”

As well as this, it's sensationally rapid in a straight line, boasts tremendous directional stability at speed, superb levels of mechanical refinement, and the sort of all-weather invincibility you take for granted from a car bearing Ingolstadt’s signature rings.

The major strength of the new generation RS6 remains its colossal engine, but this time around Audi has given it a chassis that easily challenges the likes of the BMW M5 Touring and Mercedes-Benz E63 AMG.

Should I buy one?

If the threat of losing your licence in speed-camera-mad Britian is no great concern, then absolutely. For anyone who regularly covers big distances, hankers after supercar levels of performance, and requires seating for five and lots of luggage space, there’s probably no better new car on offer today.