BIRMINGHAM, Alabama - Most cars belong on public roads, not on a race track. Porsche is one of the exceptions to that unwritten rule.

For what they call their "Spring Media Race Track Day," Porsche made five different models available to journalists for laps around the Barber Motorsports Park. Located on the outskirts of Birmingham, the Barber facility is a magnificently landscaped tract - complete with a selection of outdoor sculptures - that many believe looks more like a country club than a road-racing course.

Journalists had an opportunity to drive each Porsche on three laps around the course. The schedule included a Boxster S, Cayman, 911 Targa 4S, plus two models that might be considered the ultimate Porsches at this point: the snorting 911 Turbo and the racetrack-ready 911 GT3.

Boxster S: When they first entered the marketplace, Boxsters were seen as the economical cousins of the traditional Porsche 911. Adding the Boxster S, with its more potent 3.4-liter engine, gave the model a welcome dose of additional performance capability.

Through the twists and turns of the race course, the Boxster S handled as adeptly as most ordinary drivers could ever want or need, with sufficient power on tap to create true thrills when desired. All the primary Porsche virtues are available for far fewer dollars than any 911 would command, in a car you can drive just about all the time, under nearly any conditions. Pressing the PASM Sport button tightens up the Boxster noticeably, producing less roll and dive; but on regular roads, many drivers wouldn't even realize it was on or off.

At the Barber facility, Porsche showed its new limited-edition version of the Boxster, which features GT3 RS orange paint, black trim, and a sport exhaust system. About 500 will be produced, split evenly between base and S models.

911 Targa 4S: Porsche first offered a Targa roof for the 911 coupe way back in the mid-1960s, not long after the model made its debut as a successor to the 356 series of the Fifties. The 4S model available to journalists at Barber is the first Targa coupe with all-wheel drive. The glass roof consists of two parts, and is said to "virtually eliminate" ultraviolet rays.

With its 3.8-liter engine, the 911 Targa 4S can reach 62 mph in 4.9 seconds and hit a track speed of 179 mph, according to Porsche. Yet, a Porsche instructor noted that it's a "very functional car for year-round use."

That's one really big open space overhead in the Targa 4S. Admittedly, this version of the famed 911 feels more substantial and stable than a Boxster. It's a more serious Porsche, for those who savor the full experience offered by this German sports-car maker. The six-speed gerabox works beautifully, of course, and neatly matches the clutch action - just what you'd expect in a Porsche 911.

911 Turbo: For the most ardent Porsche enthusiasts, the 911 Turbo qualifies as the holy grail of sports cars. With a mighty 480 horsepower on tap in its twin-turbo engine, augmented by 505 pound-feet of torque, the Turbo melds traditional Porsche roadgoing vitality and tenacity with acceleration that literally pushes you back into the seat. Acceleration to 60 mph takes a mere 3.7 seconds, according to Porsche.

In most cars, such aggressive reactions might seem pretentious, if not senseless. With a car in the league of Porsche's 911 Turbo, on the other hand, such startle-the-occupants responses feel almost appropriate, perhaps even essential. Clearly, this a different breed of pure-bred sports car.

A new all-wheel-drive system was developed for the 911 Turbo, which comes to a halt using ceramic brakes with six-piston front calipers. Rear fender inlets have been redesigned, and the rear trunk is bigger. The tri-plane wing rises at 75 mph and drops back down when slowing to 36 mph. A Tiptronic automatic transmission is available, with new "fastback" operation.

Yes, it's true, the Turbo delivers a memorably exhilarating experience, precisely as promised. Acceleration when coming out of a turn is simply phenomenal. Even on a short straightaway, it's easy for a novice to top 100 mph - without pushing the pedal all the way to the floor. All-wheel-drive security is unbeatable, too. Better yet, despite all that power lurking within, this is not a difficult car to drive. When circumstances dictate restraint, you can keep it as tame as you like.

911 GT3 This is the one most participating journalists were waiting for, a rough-edged screamer that's made more for club racing than for daily commutes. As the affiliated race driver explained, it's "race-bed, high-performance, hard-core.... developed for the club racer." The frontal design gives "as little lift as possible, as much downforce is possible," and the GT3 is "not super-forgiving" in curves.

Even so, the GT3 can be driven mildly without much difficulty, once you get used to the heavier clutch pedal and intensely raucous exhaust note. Equipped with a 415-horsepower engine, the GT3 comes close to the Turbo in overall performance. Its output of 115 horsepower per liter is the highest of any model.

Though the GT3 seems raucous at first, partly because of its substantially louder exhaust, it's not otherwise that much different from a "regular" 911. Stiffer, true; but not quite dramatically so. Acceleration doesn't quite match the Turbo's, but it's close. Really close. Mainly, it doesn't leap off like a shot, but simply keeps pushing hard, no matter when you choose to let up on the gas.

Cayman: Even though the Boxster-based Cayman coupe was the least powerful of the Porsches at Barber, for many it could easily be the most enjoyable member of the quintet. Sure, the Porschephiles who are seduced by raw power will gravitate to the Turbo. Yet, those who appreciate finesse over ferocity just might prefer a spin in the sophisticated Cayman, if not its comparable soft-roofed Boxster cousin.

A Porsche driving instructor calls the Cayman "probably the best-kept secret" in the company's lineup. Based on the Cayman S with its 3.4-liter engine, which went on sale first, the base Cayman holds a 2.7-liter engine that produces 245 horsepower and 201 pound-feet of torque. That's enough for 0-60 mph acceleration in a claimed 5.8 seconds, coupled with an impressive EPA fuel-economy estimate of 23 mpg in the city and 32 mpg on the highway.

At 75 mph, the rear wing rises by 3 inches. A Ram air flip inside the intakes opens at 45 mph. Front and rear luggage compartments total a useful 14.1 cubic feet. Inside the cockpit, cupholders are hidden above the glovebox.

With its metal roof rather than fabric, the Cayman feels just enough more substantial than an open Boxster to warrant a top-choice recommendation. The five-speed manual transmission is wholly sufficient and extra-easy to manipulate, neatly matched to the lovely clutch. There's no need to feel deprived about the lack of a six-speed. Furthermore, the Cayman feels nearly as serious as a 911, at a far lower price, though acceleration is admittedly more modest when coming out of turns, and this coupe doesn't dart ahead like any of the 911s. Still, only the hardened enthusiast is likely to long for a 911 when a Cayman is at hand.

Clearly, Porsches of any stripe are not cars for everyone. They're precision machines that can be equally at home on an expressway or a race course, in traffic or on the open road. Unlike so many lookalike and act-alike vehicles on the road today, these five are guaranteed to elicit the joy of driving, even for those who aren't always so enthused about being behind the wheel. Simply put, they're special. Expensive (especially in 911 form), but special.