In a surprise move, Audi, one of the automakers responsible for breathing new life into the turbocharged engine in the last decade, has turned to supercharging for remarkable power and efficiency gains in its new uber-performance sedan and wagon based on the new A4 platform. The new mill cranks out 333 horsepower at and about 325 pound-feet of torque in a flat plane from 2,500 to 4,850 rpm. Of note, this also marks a departure for Audi high-performance and S-line engines, which tend to make considerably more horsepower than they do torque (R8: 420 hp, 317 pound-feet).
The new supercharged, 3.0-liter TFSI V-6 makes do with two fewer cylinders than the previous S4, and Audi acknowledges that the "T" in the engine nomenclature no longer denotes turbocharging but rather "the concept of supercharging in general." Much like the new Chevrolet Corvette ZR1, the supercharger design is of a twin-rotor, four-vane design, and we wonder if Audi also benefited from notable efficiency gains in supercharging recently developed by the Eaton company and employed on the ZR1 and CTS-V. The cooling effect of direct injection simplifies intercooling and enables the supercharger to be located directly behind the throttle valve, also increasing efficiency of the package.
Also big news is the rollout of Audi's new seven-speed DSG gearbox, known in this application as S-Tronic. The S-Tronic is optional, and with yet another ratio to choose from compared with the excellent six-speed unit fitted to some of its products, performance is likely to be quite breathtaking. Audi claims that the the S4 will accelerate from 0-60 mph in about 5 seconds and from 50-75 mph in about 4.4 seconds--fleet performance indeed. Standard is a traditional six-speed automatic with a torque converter. Paired with either transmission, standard, is Audi's quattro permanent all-wheel-drive system that is biased 60 percent to the rear in normal conditions.
Taking a page from Acura's SH-AWD playbook--then making a few addendums of its own--Audi introduces its active sport differential, an option with Audi's Drive Select, also itself an option on S4/S4 Avant. Like SH-AWD, active sport differential spins the outside rear wheel with greater urgency through turns. Unlike SH-AWD, Audi's system is active and effective even when the car is coasting or in between throttle applications.
As in some other Audi products, Drive Select is an option. The technology, which adjusts shift points on the seven-speed S-Tronic transmission, changes throttle characteristics, and affects steering effort, must be ordered with at least one of the following three options: the active sport differential, adaptive shock absorber control, and dynamic (active) steering.
Changes that further differentiate the S4/S4 Avant from its A4 foundations include special aprons, aluminum-look exterior mirrors, 18-inch S-design wheels, side rocker panels, a rear spoiler, and quad exhaust outlets. Inside, gray dials with white needles let you know you're behind the wheel of a special A4, and sport seats feature electric lumbar supports with pull-out thigh supports. The standard interior color is black with brushed-aluminum highlights, though carbon, birch, or stainless steel highlights are available.
Should the killer power, sybaritic interior, or sublime handling fail to remind you you're in a very special A4, the S4 badges in places like the seats, steering wheel, and key will remind you of your capability to blow the doors off the already athletic A4 sedan.
We'll have more for you from the 2008 Paris Auto Show next week, when the S4 makes its world debut. The S4 goes on sale in America next fall for a price similar to today's S4.--Colin Mathews