Munich RS is Audi's ultimate prefix, surpassing the S models and denoting maximum performance. U.S. buyers have only seen one RS model-the 2003 RS6, a wild-child A6 rumbling with a blown, 450-hp V-8. But the RS6 was actually the third Audi RS, following the 1994-95 RS2 (based on the Audi 80 wagon) and the 2000-01 RS4, a 375-hp, twin-turbocharged screamer fashioned from the first-generation Audi A4 Avant.
The new RS4 deviates from the engineering concept of its predecessors in more ways than one. The turbocharged engine has been replaced by a normally aspirated, high-revving V-8; the Quattro drivetrain for the first time features a rear-wheel torque bias; and the four-door sedan doubles the number of available body styles.
The move away from turbocharging is a big departure. The new direct-injection V-8 is ultraresponsive and addictively light-footed in the way it summons more power and whips up more torque. With 414 hp, the 2006 RS4 will accelerate from 0 to 62 mph in a stellar 4.8 seconds. The 4.2-liter unit musters its maximum brio at 7800 rpm; from there, you have another 450 rpm to play with before the limiter gently intervenes at 8250 rpm. The torque curve plateaus at 5500 rpm, where 317 lb-ft are on tap, but it is worth knowing that 90 percent of the twist action is available between 2250 and 7600 rpm.
Whereas the most recent RS, the RS6, had a five-speed automatic, the new RS4 is fitted with a six-speed stick shift. The shift linkage is quick and slick, and clutch action is light and progressive. The transmission sends torque to all four wheels, but the rears get priority. By switching the Quattro drivetrain from a 50/50 to a 40/60 front/rear torque split, Audi wants to zoom in on BMW and Mercedes-Benz. Now that the rear wheels get a bigger share of the action, the front wheels can concentrate on turn-in and braking. This results in light and linear steering, though it's still not as telepathic and communicative as those fitted to the best rear-wheel-drive competitors. Only when pushed to the point where ESP interferes does a blink of torque steer remind you that quattro is Italian for "four."
Like nearly every current Audi, the new RS4 suffers from a disappointingly harsh ride. Shod with optional 35-series Michelin Pilot Sport tires on nineteen-inch wheels, the RS4 is quite bad at coping with high-frequency transverse ridges. The staccato suspension is particularly tiring at autobahn speeds, when the car fights every expansion joint, every piece of patchwork tarmac, and every lateral groove it can find. While the underdamped steering tries to jerk off your wedding ring, the overly taut spring and damper settings convert the thinly padded, tight-fitting bucket seats into masochistic massage pods. Lowered by 1.2 inches and widened by 1.5 inches in front and 1.9 inches in back, the RS4 doesn't track as stoically as its lesser stablemates. On winding, uneven two-lanes, the front and rear axle pitch and the vertical body movements that seem to rotate back and forth around the car's longitudinal axis can affect the directional stability. It's a dynamic oddity: in a car so expressively devoid of emphatic body movements, what little compliance there is tends to work against you.
The Dynamic Ride Control (DRC)-introduced in the RS6-has been updated here and effectively suppresses yaw, roll, dive, and squat by diagonally linking the two pairs of dampers hydraulically. This wholly mechanical system provides a confidence-inspiring, ground-hugging cornering attitude that is particularly awesome on smooth tarmac, where the RS4 occasionally will lift a leg or two when going ten-tenths.
On broken-up or undulating turf, the performance is not quite as convincing, but a less extreme spring and damper setup should fix that easily. Radical is the word for the ESP calibration of the RS4. The chips cut in later, and yet they interfere with more vigor, which makes smooth driving at the limit somewhat more difficult. In the Audi, it really pays to deactivate ESP and discover the pleasures of the four-wheel slide. This applies in particular to low-grip terrain, where a brief lift is all you need to go sideways, rally-style. The gravel-and-dirt show works best in second or even third gear, which produces enough inertia to keep the car destabilized a long way past the apex.
Back on pavement, it takes plenty of space, all the torque the engine can muster, and big cojones to unsettle an RS4 enough to induce power oversteer. A bit of rain helps, if only to soften the sudden breakaway characteristics of the big Michelins. Assisted by the accurate steering, the chassis of the RS4 not only encourages mind-boggling cornering speeds, but it also maintains that crucial transparency that helps you avoid scaring yourself stupid. This car is a precision tool that deserves a precise driver and a road that doesn't have any nasty surprises.
If you do get it wrong, there are always the monster brakes to rely on. Borrowed from the Lamborghini Gallardo, the huge rotors (14.7 inches front, 12.8 inches rear) kill energy with the finiteness of a master switch, again and again, with great determination and only gradually showing faint traces of fade. In the wet, the discs are intermittently swept dry to improve response and stopping power.
Americans may be unfamiliar with the RS4, but when it finally arrives stateside next spring, they're unlikely to mistake it for a generic A4. The go-faster Audi boasts bloated and Botoxed bumpers front and rear, plenty of brightwork, additional air intakes, fat fourteen-spoke wheels, and two chromed tailpipes of pornographic diameter. Inside, we find overstyled bucket seats, classy bespoke instruments, the increasingly ubiquitous but totally pointless starter button, and a fancy steering wheel with chromed spokes and a racing-car-style flat bottom. Your left thumb is invited to push the S button, a controversial move that quickens the throttle response, ups the in-cabin noise level, and pneumatically narrows the side bolsters until it hurts. The cockpit is well laid out and well put together, but the presentation is on the ritzy side, and the driving position is too high up.
In more ways than one, the new RS4 is a move in the right direction. The brawny, normally aspirated engine is much more involving than the turbos; the brakes, grip, traction, and roadholding are simply sensational; and the recalibrated Quattro hardware removes several layers of indifference from the steering and the drivetrain. That's the good news. The bad news is the substandard ride, with its effect on the vehicle dynamics. And while the updated Quattro technology surely helps, the feedback from the chassis is still insufficiently three-dimensional. The new RS4 is a more rewarding drive than the cold and soulless RS6, but it's still a little too cool and polished to light the fire of hard-core rear-wheel-drive enthusiasts. Georg Kacher