Audi’s RS6 is one of a handful of cars that completely rearrange your ideas about what a performance car is all about. It doesn’t scream performance with wings or scoops, and only a careful eye can discern that the tires are a little fatter and the stance is a little lower.

This car does its talking when you punch the gas, and what you get is a stream-of-consciousness blast of acceleration that leaves you, well, speechless.

The RS6 is a very limited production model. Despite its $82,700 price, Audi is confident there are enough wealthy enthusiasts to snap every one brought into the country.

Audi’s A6 sedan is lovely to look at. The elegant body is a marvel of understated design, so it’s surprising to discover that this is one of the meanest, quickest four-door sedans on the planet. A 450-horsepower, twin-turbo V-8 gives it the scat very few sports car can match. Audi says it leaps to 60 miles per hour in about 4.6 seconds.

The fuel economy rating is 15 miles per gallon in the city and 22 on the highway. If you spend much time sampling the car’s power, expect mileage to be closer to 11 mpg. Drive gently and it should be able to match the ratings. The gas guzzler tax adds $1,300 to the price.

Audi says the twin-turbo 4.2-liter engine has its roots in the R8 racing car that won the 24 Hours of LeMans three years running. The production engine has five valves per cylinder, and the low-inertia turbochargers begin blowing extra power into the engine with the slightest prod of the gas pedal.

The Tiptronic automatic transmission can be shifted manually by nudging the shift lever side to side, or by using the tiny paddles on the steering wheel. The steering wheel buttons are handy, but in turns it was a disadvantage because your hands are busy turning the wheel.

Launching this car from a stop with full throttle is an eye-opening experience. Quattro all-wheel drive gives it superb traction, and it darts away from rest so deceptively that you’ve doubled the speed limit before you feel as if you’re really moving at all.

This car absolutely comes alive on secondary two-lane roads. Passing slower traffic is so easy you would think you’re operating a video game. Bushels of power are always just a nudge of the throttle away.

Given this car’s incredible performance potential, the brakes are almost more impressive than the power. Gigantic front discs are gripped by eight-piston calipers. Most ordinary cars have two- or four-piston calipers. These brakes are straight from the track. Top speed is electronically limited to 155 miles per hour. Without the governor, top speed is likely to be 180 mph or better.

The all-wheel-drive suspension is buttoned down nicely. The ride is very purposeful, but not harsh or uncomfortable. The car does feel a little nose heavy, as one might expect, but again, all-wheel drive helps provide handling balance. The RS6 whips through turns with negligible body lean, and at high speeds it feels so secure that one suspects a giant hand is holding it down.

The cabin is big enough for five, although four is a more practical number because sitting in the middle of the back seat would not be very comfortable.

Typical of other A6s, the RS6 has superb materials and fit throughout the cabin. The front seats are deep, firm and supportive. I did notice a bit of a backache after a couple of hours behind the wheel, but that could be as much me as the seat.

The RS6 is a rich man’s rocket. Those fortunate enough to afford one, or find one, will find out that the car is a delight every time you turn the key.