It's called the rearview mirror effect, the instant psychological reaction to another machine rushing up to your tailgate, and it's more complex than you'd think. A Ferrari's inimitable front end rushing up can provoke envy, even blocking tactics. But today, in ABT Sportsline's AS5-R, with lights ablaze and venomous warning colors running down its length, the local traffic virtually throws itself off the road to avoid a potentially painful bite. At least we warned them.

Of course the base S5 isn't that kind of car. It's a refined executive work tool with a stylish look and sporting pretensions. Its psychopath cousin, the RS5, is just over the horizon, and charging hard towards us, though, and this car right here is the best indication of how it will behave. It's going to be freakin' awesome.

It won't come with the warning colors, which is probably a good thing. This matte white car would have looked better, more fitting, without the fake carbon-fiber film, red stripes, vents, splitter and gaping diffuser that informs the outside world of the car's venom. But then this is a show car that first surfaced at Geneva, so we can forgive the gang colors. Especially when it goes like this.

ABT is a supercharging specialist and performed a work of art with the V8. The Kempten firm has a rolling road and a dyno that could easily belong to a major manufacturer, and its hand-in-glove relationship with Audi shows the level of respect that the engineering world has for its work. Ramping up power by 40 percent can be a recipe for disaster, but this car is almost bulletproof. This supercharger conversion spent several days lapping the Nürburgring on the dyno, hours at full speed on the rolling road and was then punished mercilessly on the open road. They've already tried to break it, so the customer won't, and there is some serious cooling plumbing underneath the hood to keep the V8 from sweating, let alone melting.

The Lysholm twin-screw supercharger sits inside the 4.2-liter's vee and with 8.5 psi of boost it gives the AS5-R 503 hp to play with at a heady 6800 rpm. That's 53 more than the RS5 will come with, which along with 457 lb-ft of torque makes a monster difference on the road as zero-to-60 drops from 4.9 seconds to a sports-car-baiting 4.3.

Forget the BMW M3 that sits firmly in Audi's sights with the upcoming RS5; this car goes to war with an M5, and the acceleration just keeps on coming right through the gears, all the way to a 181-mph top speed. Getting the gears to slot home is another story; the short-shifter takes the kind of muscle that doesn't belong in a big cruiser like this, and indeed ABT's technicians were due to soften it after our drive, but it adds a new sporting dimension to the drive and transforms the car's character. Most RS5s will come with the flappy paddles, but this here is what they really need.

And the noise, a heady concoction of liberated, unmuffled V8 roar and high-pitched supercharger whine is something that the factory will never come close to. Even the RS5 will be inhibited, muted, quiet, while ABT's machine sends a sonic boom through the cabin on a hard charge. It's one of those noises that makes me pin the throttle on every single straight.

The height-adjustable suspension doesn't quite offer the precision of Audi's Magnetic Ride, but then it's a whole new world compared to the standard S5 kit. The H&R kit gives 40mm of slack to play with, though an adjustable suspension seems a little overkill for a car of this ilk. In truth, most customers will likely be more than happy with the alternative 25mm lowering springs.

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