Although not cheap by any means, the S4 does offer a mouth-watering array of features and improvements over the regular A4 Sedan after which it is modeled.

Starting things out is a 2.7-liter, twin-turbo V6 engine. Sporting twin intercoolers, dual-overhead cams, five valves per cylinder, variable valve timing for the intake camshaft, and optimized combustion chambers, the engine generates 250 horsepower and 258 foot-pounds of torque. Audi has designed the engine to provide much of its power low in the revband. Consequently, the S4 makes quick work of freeway on-ramps and passing maneuvers. Audi gives buyers of the S4 a choice of transmissions; there's a six-speed manual transmission or a five-speed Tiptronic automatic transmission.

All S4s come with Audi's quattro all-wheel-drive system, which constantly monitors the grip of the tires. When one of them starts to lose traction, the quattro system automatically applies power to the tires with the most adhesion. Audi says this latest edition of the quattro all-wheel-drive system is capable enough to allow the car to get underway even when only one wheel has reasonable traction.

An S4 Avant is made available for 2001, replete with the 2.7-liter, 250 horsepower, V6 Bi-turbo engine, and such niceties as a retractable luggage cover, retractable dividing cargo net and aluminum-finish roof rails. It's perfect for anyone who needs utility but refuses to give up stellar sport-sedan performance.The suspension and braking components of the S4 are well tuned. Major items of note are performance-tuned shocks and springs, and unique 17-inch wheels with 225/45R17 tires. This year, the S4 Sedan gains the Electronic Stabilization Program as standard equipment.

The interior retains the same architecture found in the A4, which means an attractive design and an adequate number of features. Special leather upholstery covers standard power seats, and contrasting color suede inserts can be had when ordering the sport interior package. Other options to consider include a sunroof, heated front seats, a six-disc CD changer, and a Bose premium audio system. For safety, there are standard front and head-mounted airbags.

Outside, the S4 differs from regular A4s (not that the A4 is exactly regular, of course) by having the aforementioned 17-inch wheels, larger front air-intake openings, and S4 badging.

The S4 driving experience is a pleasure. The S4 is softer than a BMW M3, but its forgiving nature comes at the expense of pure handling excellence. Taken as a whole, however, we think the 2001 Audi S4 is quite the contender in the sport-sedan market.