Audi engineers put a lot of work into making the 2007 RS 4 more than a glitzed-up run-of-the-mill sedan. The primary ingredient is a 4.2-liter, dual overhead cam, 32-valve V8 engine pushing 420 horsepower at 7,800 rpm and 317 lb.-ft. of torque at 6,000 rpm, 90 percent of which is available between 2,250 and 7,000 rpm. This potent aluminum power plant uses a six-speed manual transmission to direct energy to each of the 19-inch alloy wheels and 255/35 Michelin Pilot Sport tires. The popular Audi S4 also houses a 4.2-liter V8, yet the RS 4’s version has been overhauled with all new internals; even the aluminum used to construct the block is different. The RS 4 also utilizes a tweaked exhaust system with two large oval outlets rather than the S4’s quad tips, and an S button on the instrument panel opens things up for a louder, deeper sound while also putting a quicker response behind the aluminum accelerator pedal. All told, the amped RS 4 pushes an additional 80 ponies and 15 lb.-ft. of twist when compared to the revered S4 and reaches 60 mph in 4.8 seconds instead of 5.3. The top speed is electronically limited to 155 mph, and maximum revving takes place at 8,250 rpm.