Steady on. We’ll get to the relative merits of the new Audi RS5 versus the German cars it so obviously targets very shortly. When the German big three go to war, we always want to define a winner. But we need some context. Though this looks like an A5 peppered with extra nostrils on some spangly rims, so much about the RS5 is new. Like, new new.For £62,900, you get precisely the same amount of power as the old RS5 – 444bhp – and two fewer cylinders. Yup, downsizing bites.The RS5 forfeits its old naturally aspirated 4.2-litre V8, partly because it’s a pain to duck it under the CO2 barrier, and partly because it simply can’t summon the immense torque offered by the twin-turbocharged onslaught of the C63, M4, and Alfa’s Giulia Quadrifoglio. In comes a 2.9-litre, bi-turbo V6. The die-hard engine experts among you will have noticed that means the new RS5 actually has a slightly smaller engine than the current S5. It’s 100cc down, but a whole turbocharger to the good, and that means massive twist is on hand. You get 442lb ft over a massive rev band – 1,900rpm to 5,000rpm. The old RS5’s V8 teased you until 4,000rpm for its ultimate overtaking punch, which, when it eventually arrived, was 37lb ft weaker.The point-to-point pace is bloody rapid. Is there turbo lag? Yes, a thimble-full – it’s more perceptible than a C63 or M4 falling off boost. But it’s a momentary, vanishing delay: maximum torque for over 3,000rpm of the 6,750rpm rev-band makes the new RS5 intergalactically more urgent through the gears than the last car. Raw stats show the RS5 to be mightily fast. Audi Sport claims 0-62mph in 3.9 seconds, which is what BMW claimed for the brand-new M4 CS (which will set you back another £30,000…). Okay, all of that comes from the Audi’s Quattro, all-wheel-drive advantage over the RWD M4, and all of these rocket-sled sprint times are mostly sorted out by launch control, which no-one in the real world ever deploys for fear of looking like a frightful tool at a zebra crossing. That said, you just know the Audi will nail that time – or even dip below it – on any surface, in any conditions. If you like your performance accessible and ready to wield with nary a care or consideration – and I happen to – then this thing’s a straight-line weapon. A ruthless distance dispatcher. I don’t think 0-100mph in eight or so seconds is too much of a stretch.Because the standard A4 and its A5 sister are so refined now – Audi’s made such an effort to dampen out wind, tyre and engine noise – the RS5 isn’t a whole lot rortier than an S5, really. It’s not as guttural of the Alfa Giulia, and there’s not a whole load of tone to the noise. You get some exhaust flatulence on the overrun, and some cracks on the upchange, but the noise, like the surging, consistent power delivery, builds up a picture that the RS5 is quite a relaxed mini-super coupe.It’s lighter – 60kg as standard, but you can diet harder to the tune of a 3kg if you spec the £3,250 carbon fibre roof that BMW throws in for free on an M4. And the RS5 feels heavier than it is. Some of that is Audi’s own fault: enter Dynamic Steering, which is back up to its old tricks here, making the car feel unsettled and agitated on the way into a corner with its wildly variable steering speed and totally numb feedback. Why do we need this rubbish for the sake of having a slower, less nervous rack on the autobahn? It’s hardly as if the car’s inherently unstable. A rear-wheel steer system would suit it miles better. You have to learn how to drive to the RS5’s strengths to get the best from it, unlike its purer rear-drive rivals. Initially the car almost lurches into the bend because the steering is so haphazard. But be patient with that, get it settled then just as you spot the exit of the corner, long before you start to open the steering, nail the loud pedal for all you’re worth. That’ll wake the Sport Differential up and get torque marshaled to the rear wheels, for the neutral, mega-traction corner exit stance we know from the Audi S5.Some of the test cars had Alcantara steering wheels, gear selectors and door trim, which looks and feels gorgeous but does feel a bit incongruous. Like wearing running spikes to your wedding, the setting seems a bit formal for such hardcore details. As per the S5, the seats don’t drop anything like as low as an M4/C63/Giulia’s, and they prioritise long distance back support over lower-body hugging bolsters. Which brings me back to something that’s been nagging me ever since I first drove the S5, and heard the RS5 was dropping its V8.Look at the spec. S5 and RS5 are now both turbocharged V6-powered, four-wheel drive, auto-shifting coupes. Okay, the RS5 has double the turbos, but if you actually understand how much that differentiates the two cars, you’re in a fraction of a percent of the population. Drive the current S5, and compared to the old car, it’s very different. Much more easy-going and relaxed. The noise is muted. Its eight-speed auto doesn’t shift with anything like the snap of the old seven-speed dual-clutcher. It’s a nice everyday car, but has very little ‘bite’. So I’ve suspected since driving it that the S5 had been deliberately neutered, and shifted into a mini-GT role, so the similar-on-paper RS5 could grow devil horns and be much more aggressive. To have its own space, and own character.Absolutely not. For many miles in the RS5 I kept checking the ‘R’ logo on the steering wheel. Had I been led up to it blindfolded, I might have taken it for a healthy S5. I recall the old RS5 tackling bumps like a V8-driven wheelbarrow. Knock the new one’s dampers into Comfort and you have an incredibly soothing, cosseting, pliant bit of kit. It’s so, so much less firm than the Alfa/AMG/BMW opposition. And quieter. And less aggressive. And it doesn’t feel quite as quick, given it’s 50bhp down on the first two of those three. So it takes a long time to warm to the RS5, because you initially find yourself wondering why you’d pay the £15,000 extra over an S5. I think Audi Sport has spent a long time studying rivals and concluded that the power and aggression of the RS5’s contemporaries doesn’t square with how Audi customers use their cars. As in, they bathe in the comforting security of Quattro, and prioritise point-to-point speed over white-knuckle thrills. So on that basis, the new RS5 is a clever car. And it’s a monumental improvement, in every department except noise, over its deeply flawed predecessor. I reckon Audi’s made a car that’s deliberately less heart-thumping, adrenaline-soaked than its rivals, all in the hope more folks will enjoy living with it. It’s not the sort of progress we were expecting.