Few cars have impressed me enough to make me look forward to my 31-mile urban commute, but the new Audi S4 certainly has. It's the kind of car that inspires curiosity and selfishness among the staff-like a game of "I have a secret" nobody else knows I'm playing.

"So, how's that S4? I heard it's a lot of fun," lobs a colleague. "It's alright; pretty quick, I guess," I sheepishly reply, "but I'll need at least another night in it to be sure." Another advance foiled, but how long can I keep this up? Damn. What if the boss wants to drive it? As our temporary automotive inventory now stands, he'd have to want it pretty bad to trade our new long-term Porsche C2 for the Audi S4. I'm safe for now-phew, or in German, "fe."

What is it about the S4 version of Audi's already fun and popular compact sedan, the A4, that doesn't promote sharing? A twin turbocharged 250-horsepower 30-valve DOHC V-6 connected to Audi's banned-from-racing Quattro all-wheel-drive system, a six-speed manual transmission, and four-piston brake calipers make it the quintessential wolf in sheep's clothing, the epitome of a sleeper, and if I had my way, the best-kept secret in the automotive world.

What's most remarkable about the S4's engine-please forgive my unsophisticated description-is that it feels torquier than it does horsepower-ful. Because its maximum torque output of 258 pound-feet is available (and constant) from a mere 1850 rpm right up to just under 4000 rpm, motoring away from a low-speed corner or stop doesn't necessarily require a downshift. Even from a low 1500 rpm, the generous shove of a seatback encourages you to push the pedal closer to the floorboard.

The engine's table-flat torque curve and and daylong powerband are perfectly happy and able to push what might be considered a tall gear. Around town, third and even forth gears are adequate for most situations. But once you arrive at your favorite cloverleaf, onramp, or serpentine backroad, you'll find six gears from which to choose, bushels of exhilarating torque, and two wheels pushing while two pull you around corners as if you were tethered at the apex. From about 4500 rpm, when things start to get really interesting, all the way up to its 6800-rpm redline, you'll notice many so-called performance cars left in your wake. You'll find yourself muttering, "It seems too easy to be true-can I really be driving this car at this speed, around this bend?"

Riding only about an inch lower than the sport-package-equipped Audi A4, the firmer S4 gets around on low-profile Bridgestone Potenza rubber stretched over standard 17x7.5-inch Avus-style rims. Further differentiating itself from the A4 are the S4's close-coupled twin turbochargers, each squeezing 16 pounds per square inch more air into a slightly smaller-volume engine (2.7 liters versus 2.8 in the A4). The 0.1 liter was displaced by an extra 1.5 millimeters of cylinder wall thickness to handle the added pressure and diminish engine noise.

Inside is an impressive amount of standard equipment, such as driver and passenger 10-way power sport seats with silky Nappa leather upholstery, sport steering wheel, eight-speaker 120-watt AM/FM/CD/cassette sound system, one-touch power windows, power mirrors, central locking, fully automatic climate control, electronic cruise control, full-size spare tire, dual airbags, and new "sideguard" curtain airbags spanning from A- to C-pillars.

The S4's only options are convenience package, cold-weather package, sport interior package, Bose sound system upgrade, Motorola hands-free phone, and navigation system. Later this year, the S4 will be available with a five-speed Tiptronic automatic transmission at no extra charge. Available in nine exterior colors, our tester was an impossible-to-ignore Imola yellow. Hardly the color I'd choose to fly low and avoid radar, but I managed to surprise more than one wide-eyed wannabe boy racer who thought I was just some yuppie in a poseur sedan.

Because the S4's driving dynamics are are so good, discovering its subtle handling limits is an exercise best saved for a racetrack or deserted parking lot. By the time you reached any kind of limit on a public road, you'd be well into multiple hundreds of dollars in likely fines. Audi's patented all-wheel-drive system allows for throttle-on, controllable drifts with less potential for off-throttle precariousness that high-performance two-wheel-drive cars normally exhibit. In other words, within the laws of physics, it's hard to do something that upsets the car's intended telemetry, and if you somehow manage to break the sticky tires away from the pavement (such as a slight understeer in a fast corner), all that needs to happen to make it right again is judicious throttle application and a steady hand at the wheel. This is the method track tester DeMere used to generate an impressive 67.1-mph slalom pass. On the skidpad, with a more delicate hand, the S4 clung to the pavement with 0.89 g of grip. And although we didn't have the opportunity to test this car in inclement weather or at acceleration-sapping altitude, we know the popularity of turbocharged all-wheel-drive vehicles in the Rocky Mountains and Eastern Seaboard must have something to do with their abilities in various types of precipitation. The Audi S4 will quickly earn top honors there, as well.

What the less powerful A4 Quattro gives up in acceleration due to the added weight of an all-wheel-drive system, the S4 more than makes up for with a street-fighting 0-60-mph time of 5.5 seconds-the same as the last BMW M3 sedan we tested. The quarter mile became a memory in 14.1 seconds at 98.3 mph. This kind of acceleration is usually the hallmark of a car with fewer than four doors, a cramped cockpit, and a harsher ride. Any quicker, and it would be running with Corvettes, Carreras, and $70,000 Mercedes-Benz E55 AMGs.

The S4 is not for everyone. It tends to be more sporting than pampering; it absolutely begs to be abused, and its interior is a little too intimate for some folks of large girth. For all these reasons, Audi offers the same wonderful engine in a different wrapper called the A6 2.7T. But that's a different story.

Suffice to say that I've now revealed my secret and the word is spreading fast. In fact, our photographer had the following to say after just one drive, "This thing rips! It's got more punch than Mike Tyson at a street fight, but it's always predictable and won't bite your ear off." He also told me that the perfect personalized license plate for the car is already taken by a neighbor of his. It reads, "Audios."

2000 Audi s4 Quattro GENERAL Location of final assembly Ingolstadt, Germany Body style 4-door sedan EPA size class Compact Drivetrain layout Front engine/all-wheel drive Airbag Dual front, side, head Show All

POWERTRAIN Engine type 90º V-6, twin turbocharged, cast-iron block, aluminum alloy heads Bore x stroke, in./mm 3.19 x 3.40/81.0 x 86.4 Displacement, ci/cc 163.0/2671 Compression ratio 9.3:1 Valve gear DOHC, 5 valves per cyl. Fuel/induction system Seq. EFI Horsepower, hp @ rpm, SAE net 250 @ 5800 Torque, lb-ft @ rpm, SAE net 258 @ 1850 Horsepower/liter 93.6 Redline, rpm 6800 Transmission type 6-speed manual Axle ratio 4.11:1 Final-drive ratio 2.81:1 Recommended fuel Premium unleaded Show All

DIMENSIONS Wheelbase, in./mm 102.6/2607 Track, f/r, in./mm 58.9/58.7/1498/1490 Length, in./mm 176.5/4483 Width, in./mm 72.8/1848 Height, in./mm 55.8/1418 Base curb weight, lb 3594 Weight distribution, f/r, % 59/41 Cargo capacity, cu ft 49.7 Fuel capacity, gal 16.4 Weight/power ratio, lb/hp 14.4 Show All

CHASSIS Suspension, f/r Multilink, coil springs, anti-roll bar/ upper and lower control arms, coil springs, anti-roll bar Steering type Rack-and-pinion, variable power assist Ratio 16.2:1 Turns, lock to lock 3.1 Turning circle, ft 37.4 Brakes, f/r Vented disc/disc, ABS Wheels, in./material 17 x 7.5 aluminum Tire size 225/45YR17 Manufacturer/model Bridgestone Potenza RE 040 Show All

PERFORMANCE Acceleration, 0-60 mph,sec 5.5 Standing quarter mile, sec/mph 14.1/98.3 Braking, 60-0 mph, ft 118 Lateral acceleration, g 0.86 Speed through 600-ft slalom, mph .67.1 Est. fuel economy, mpg, city/hwy. 16/25 Est. range, city/hwy., miles 262/410 Show All

PRICE Base price $37,900 Price as tested $41,000 (est. )