When does very fast become too fast? It’s a question we’ve been thinking about a lot since testing the new Audi RS7 Sportback on UK roads for the first time. Based heavily on underpinnings from the RS6 Avant, the four-door coupe-styled saloon you see here is in direct competition with the Mercedes-Benz CLS Shooting Brake and BMW’s 6 Series Gran Coupe. It’s also quite ludicrously fast. It’ll do 0-62mph in 3.9 seconds, but that’s only part of the story. It’s the way its 4.0-litre twin-turbocharged engine relentlessly yanks you up the road that really impresses. From a standstill there’s absolutely no wheel-spin to speak of, just pure traction. This neck-snapping acceleration is made possible thanks to Audi’s Quattro four-wheel drive system, which also produces titanic levels of grip through corners. It genuinely feels as though this car is almost too capable for UK roads – with the amount of speed possible in bends and the accelerative forces on offer it’s unlikely you’ll be able to find a road to truly exploit it. The steering is nicely weighted and offers enough feedback to point the car in the direction you want to go and have the confidence it’ll play ball. Fortunately the package also includes carbon-ceramic brakes. These are very impressive indeed, with a progressive pedal feel and almost unbelievable stopping power. They’re also not going to fade, even when abused repeatedly on a race track. Our car featured the optional Dynamic Plus Package, which means that ferocity continues as you fire through the eight gears in the smooth yet lightning-quick automatic gearbox all the way up to a top speed of 189mph. That’s not all you get for your ten grand, though.