Audi's supercharged 3.0-liter V-6 in the A7 Sportback is such a lusty, powerfully good engine that it makes opting for the S7 and its 4.0-liter turbo V-8 seem superfluous. The 4.0-liter turbo S7 simply doesn't feel that much quicker or more powerful than the A7's V-6. In fact, Audi says the S7 was not designed to compete with the BMW M5, the Mercedes-Benz E63 AMG, or the Cadillac CTS-V, anyway.
That car is the Audi RS7 Sportback, which premiered Monday at the Detroit auto show. It starts with the 4.0-liter TFSI but doubles the twin-scroll turbo count to help produce 560 horsepower (European; which translates to 509 hp in the U.S.), up from the S7 engine's 414 hp. Torque is 516 pound-feet versus the S7's 406. By Audi's estimate, this will get you to 60 mph from a standing start in the big hatchback sedan in just 3.9 seconds, or 0.9 second better than the company's estimate for the S7.
The 4.0 is an unusual engine, with the exhaust valves on the inside and the intake on the outside of the vee. The two twin-scroll turbos make a maximum 1.2 bars of boost pressure and are placed with the intercooler, inside the vee, for short gas paths and quicker response. The RS also has its own specific engine management. The driver can change the engine's note via a button that controls exhaust system flaps, and a sport exhaust is optional.
Audi also adds its version of power shutoff, called cylinder on demand (COD) to the RS7's engine. Electromechanical actuators close off the valves for cylinders 2, 3, 5, and 8 to make it a 2.0-liter under light loads. Converting from the European cycle measurement, Audi claims fuel efficiency averaging 24 mpg.
Quattro permanent all-wheel-drive, the eight-speed Tiptronic transmission, and torque vectoring all are standard. A seven twin-spoke 20-inch forged wheel is standard, and three designs of 21-inch wheels are optional, as are 16.5-inch carbon-fiber ceramic disc brakes painted anthracite gray.
RS7 buyers will have a choice of adaptive air suspension, which lowers the car by 0.8 inch, or sport suspension plus with dynamic ride control. The latter uses steel springs and three-stage adjustable dampers. The standard electromechanical steering has been tuned specially for the car, and a dynamic steering setup with stepless variable boost and ratio is optional.
The RS7 interior gets white scales and red needles on black-faced gauges, a flat-bottomed, three-spoke, leather-wrapped steering wheel; special boost pressure and oil temp gauges; and a lap timer. It feature carbon inlay trim and has highly bolstered black Alcantara and leather sport seats or an all-leather option.
How can you tell an RS7 from an S7 or A7? Take a look at the bumpers - they're exclusive to the hairy twin-turbo car. There's also a high-gloss black honeycomb grille, matt aluminum trim, and a power extending spoiler, plus a diffuser and twin elliptical tailpipes.
So it looks the part. Whether it feels quicker -- both in a straight line and through turns -- than the S7 and by extension the A7, will have to wait for our first drive.