With the current crop of ultra-performance sedans coming out of Germany, Audi has typically been left in the shadows of the AMG products from Mercedes-Benz and the M products from BMW. Now, with the 2007 Audi RS 4, the folks from Ingolstadt show they are serious about making a mark in this prestigious segment.

Essentially an S4 taken to a higher level, the Audi RS 4 has an even more powerful V8, bigger brakes, a more sporting chassis and exclusive interior trim. It also has a much higher price tag. Subtle yet powerful design differences, such as aggressively flared wheel openings, a discrete deck lid spoiler and 19-inch, double-spoke wheels separate the RS 4 from the S4.

In addition to the car's 420-horsepower V8, Audi's well-developed quattro all-wheel-drive system gives the RS 4 an edge over its rear-drive rivals. Sure, traction control and stability control (which of course come on the RS 4 as well) will help the competition in bad weather. But nothing can equal the grip and control all-wheel drive provides on slippery pavement.

For all the important yardsticks by which an ultra-performance sedan is measured, the Audi RS 4 does itself proud. Acceleration, braking, cornering and ride quality are all superb. And while there's no doubt its price tag is significantly large, for driving enthusiasts who live where the rain and snow sometimes fall, the RS 4 is the only way to fly.

The 2007 Audi RS 4 is a compact ultra-performance sedan that's based on the S4 performance sedan, which in turn is based on the A4 entry-level luxury/sport sedan. Standard features include 19-inch wheels with 255/35 high-performance tires, Dynamic Ride Control suspension, bi-HID headlights, Recaro sport seats with power adjustment, and front seat heaters. Napa leather upholstery, carbon-fiber cabin trim, dual-zone automatic climate control, a 10-speaker audio system with six-disc CD changer, a sunroof and rear park assist are also standard. A premium package is optional and includes auto-dimming mirrors, a navigation system, an upgraded Bose audio system with Sirius satellite radio, heated rear seats, Homelink, a power rear sunshade and Bluetooth capability.

A 4.2-liter V8 engine powers the Audi RS 4. Equipped with direct fuel injection and sporting a 12.5:1 compression ratio, this powerhouse makes 420 horsepower and 317 pound-feet of torque. A six-speed manual gearbox (the only transmission offered) sends the power to all four wheels through Audi's quattro all-wheel-drive system, which has a 40/60 front-to-rear power split in this application. During instrumented testing conducted by Inside Line, an RS 4 shot to 60 mph in 4.7 seconds and ran the quarter-mile in 13.2 seconds at nearly 107 mph.

Highlights of the cabin include Recaro seats with 12-way power adjustment, carbon-fiber trim on the dash and doors, and contrasting piping on the napa leather upholstery. Fine fit and finish, an Audi hallmark, are evident throughout. To allow cargo flexibility, the rear seat is a split-folding design that also incorporates a "ski sack" so long, skinny items can be transported inside the car while still carrying four passengers.

With more than 400 horsepower and the grip of all-wheel drive, the RS 4 has no problem catapulting itself off the line or out of a corner. With a broad torque spread, there's always power on tap. Apart from the incredible acceleration, the RS 4 makes a strong showing in the braking and handling departments. Through the curves, the RS 4 is a composed master despite is hefty curb weight. Inside Line testers recorded a slalom speed of 70.6 mph, which puts the RS 4 in an elite circle of cars with four doors. Confidence and grip from the front tires are superb, balance is good and steering feel at speed is better than any Audi car we've ever driven.

Stability control, antilock brakes with brake assist, front seat-mounted side airbags and full-length head curtain airbags are all standard on the 2007 Audi RS 4. Official crash tests have not been performed on the RS 4, but one could assume with fair confidence that its scores would be similar to those of the regular A4 sedan.