2008 Audi RS 4

Audi says the all-wheel-drive RS 4 "highlights the engineering and technological expertise of Audi more than virtually any other car." This auto was developed by Audi's oddly named (at least to American ears) "quattro GmbH" high-performance division and closes the gap between a sports car and a sports sedan.

The RS 4 has nearly the immediate responsiveness of a production-based race car and, says Audi, "continues the tradition of quattro GmbH in bridging the gap between motorsport and everyday motoring."

Costly
Such a car always costs a lot, so it's no surprise that the RS 4 lists at $66,000, not including a $2,100 gas guzzler tax. Estimated fuel economy is only 14 mpg in the city and 21 on highways, and premium fuel is needed.

The RS 4 looks racy, with large front air inlets for engine cooling, flared wheel arches to accommodate huge tires on 19-inch wheels, flared side sills and a rear spoiler deftly integrated into the trunk lid and side panels.

My test RS 4 had sunglasses-shattering Imola yellow paint that really made it stand out. I was surprised to find that it wasn't an optional color.

Avoid Curbs
However, the front spoiler is ridiculously low for street driving and thus can easily be damaged. And ultrawide tires have almost no sidewall area—leaving the costly, attractive wheels with virtually no scuff protection if they accidentally nudge curbs.

Compared with a standard A4, the RS 4 sits 1.2 inches lower and has a wider track, increased by 1.5 inches up front and nearly 2 inches at the rear.

Impressive V8
Powering this rocket is a 420-horsepower V8. It revs to a race-style 8250 rpm. However, unlike most race engines, the 4.2-liter V8 has smooth, linear power delivery from low to high rpms.

The engine has a lofty 12.5:1 compression ratio—just like the fastest 1960s American muscle cars that are drawing such big bucks these days—and very efficient direct fuel injection.

No Automatic Transmission
No automatic transmission is available, not even one with steering-wheel paddle controls for lightning-fast shifts rarely needed during normal driving.

Rather, the engine works with a more traditional 6-speed manual gearbox with a short-throw floor shifter. The clutch has a long-throw but positive action—there's no need to fear stalling the engine because of a clutch that abruptly engages near the top of pedal travel.

Sizzling Acceleration
Audi says the RS 4 does 0-60 mph in 4.6 seconds, and one magazine found it hit 100 mph in just 10.7 seconds. That's right in line with a Porsche 911 Carrera 4S, which is a lighter two-seater. Top speed is electronically limited to 155 mph.

Pressing a "sport" button on the Audi's dashboard causes slightly quicker throttle response and a more aggressive exhaust sound. There's also a stopwatch with a lap timer function that Audi says is a "useful extra for those special track days so beloved of RS 4 drivers." (While new to America, the first RS 4 debuted in Europe in 1999.)

All-Wheel Drive
Some 58 percent of the RS 4's weight is up front, but it doesn't feel nose-heavy, It handles virtually like a well-balanced rear-wheel-drive auto, at least off the track. That's largely because of its advanced all-wheel-drive (quattro) system that supplies 60 percent of power to the rear wheels during regular driving.

The RS 4 also has a high-performance suspension and Audi's Dynamic Ride Control, which reduces body roll and pitch. And there's an electronic stability control system, which includes an electronic differential lock, traction control and powerful anti-lock brakes with electronic brake force distribution for consistently sure stops.

Steering is precise and stopping distances are impressively short, with good brake pedal feel. Although firm, the ride is supple, although it occasionally became a bit jumpy on uneven Chicago area freeway surfaces.

The RS 4 has lots of weight-saving aluminum but still tips the scales at a hefty 3,957 pounds. Put that weight with the high horsepower and sizzling performance and you can see why this Audi will never win fuel economy runs.

Very Refined
The RS 4 wouldn't be much fun during normal driving if it were loud, temperamental and uncomfortable. But it's quiet, refined and loaded with comfort, convenience and safety features—one reason it's so heavy.

This Audi is so well-equipped that the only major option is a $4,700 Premium Package. It contains items including a navigation system, glove box CD changer, SIRIUS or XM Satellite Radio, Bose premium sound system and heated rear seats. Front-seat side airbags are standard, while rear side bags cost $350.

The quiet, upscale interior is filled with leather, aluminum and carbon fiber. The front bucket seats are supportive and gauges can be easily read. Major controls are easy to use.

Tight Rear Seat
But the back-seat area is tight, and a stiff rear center seat area is best occupied by a pull-down armrest.

The trunk is large, with a low, wide opening and a lid that moves well up and out of the way on hydraulic struts. Rear seatbacks flip forward and sit nearly flat to enlarge the cargo area.

The RS 4 is exclusive, and will outperform most cars while used for commutes or weekend chores and sports. Considering that, maybe it's not so costly, after all.