Audi is sticking two exhaust pipes up to the environmental brigade with this, the ridiculously powerful new RS6, revealed here for the first time.The new RS6 packs a faintly ridiculous 572bhp from the twin-turbo 5.2-litre V10 that's been squeezed beneath its lightweight aluminium bonnet - 145bhp more than its twin-turbocharged 4.2-litre V8 predecessor.That surfeit of power instantly makes the RS6 to the leader of the muscle-saloon pack; the Mercedes E63 AMG has a mere 503bhp and the BMW M5 a trifling 500bhp. Then again, Audi already produces a 429bhp 5.2-litre V10 S6, so it really needed to ramp up the power for the RS6. Providing the shove is a tweaked version of Audi’s 90-degree 40-valve 5.2-litre V10 petrol engine with twin turbochargers, air-to-air intercooler and the latest direct injection system. Max power is developed at 6250pm, with peak torque of 480lb ft (96lb ft up on the M5; 15lb ft up on the E63) arriving at just 1500rpm.Audi says that the RS6 will leap from 0-62mph in 4.6sec – faster than the M5, and as quick as the E63. The difference, however, is that the Audi is likely to be able to manage that performance whatever the weather, thanks to standard quattro four-wheel drive.As in the first-generation RS6, drive is fed through a six-speed automatic gearbox with steering wheel mounted shift paddles. This time, however, the beefed-up Torsen differential based arrangement doles out 60 per cent of the power to the rear and 40 to the front, to provide what Audi describes as improved levels of traction and more rear biased handling.There's also a reworked suspension, with the same four-link arrangement up front and multi-links at the rear as the S6, but with radically altered elasto-kinematic properties to take advantage of the increased power being put through the rear wheels. Also standard is Dynamic Ride Control, a mechanical system that alters damping during cornering to counteract roll and pitch.The looks aren't quite as pumped up as the performance: for a car that packs over a hundred horsepower more than a Porsche 911 Turbo, we think it's rather subtle.Up front there's a more heavily profiled front bumper with larger cooling ducts, a revised grille with brushed aluminium frame, and the now-obligatory-for-Audi LED daytime running lights.Along the flanks, the RS6 flexes its biceps, with massively bulging blistered wheelarches that recall the original Quattro. Wheels are 19-inchers as standard, shod with 255/40 tyres, but 20-inchers with 275/35 rubber are optional. At the rear is a pair of chromed oval tailpipes, set within a rear bumper that has a full-width diffuser for high-speed stability. There's also a subtle spoiler. We've only got photos of the estate so far, but Audi will be building a saloon as well, giving the RS6 the potential to squash not just its German rivals, but also the forthcoming new Jaguar XF-R.The RS6 arrives in the UK in April 2008, when it's expected to cost around £70k. Just don’t ask about the CO2 emissions.