Ah, at last. Mercedes-Benz’s SLK roadster has finally arrived. This is my fourth turn in the wedgy little two-seater with the folding steel top. But this is the first one that I can say without reservation has the equipment and performance to qualify as a bona fide sports car. And all it took was an extra-fine V-6 and a slick-shifting, six-speed transmission.

The first three SLK models were not quite right. The first one I had back in ’98 seemed rushed into production to compete with the new flock of latter-day roadsters coming out of Germany and Japan.

That SLK 230 Kompressor contained a four-cylinder engine equipped with a supercharger (a.k.a. kompressor in German) and an automatic transmission. Performance was uninspiring, despite the 185 horses claimed for the engine, which also was harsh and lacking in low-end torque. And the automatic was just all wrong for a reputed sports car. Mercedes brass said that market studies showed Americans were not interested in shifting for themselves.

Wrong. Competing sports cars, from the retro-themed Mazda Miata to the desirable Porsche Boxster, were being sold mainly with manuals.

Mercedes, finding its SLK at the bottom of most drivers’ sports-car shopping lists, began offering SLKs with the option of a five-speed manual. But it was a balky unit that still blunted the experience. That was the second version I drove.

Then came the third, an SLK 320 fitted with Mercedes’ sparkling 3.2-liter V-6, which also powers the fine E320 sedan. But once again, this test car came with automatic. Grrr.

Now, I’ve had the SLK as it should have been in the first place, equipped with the smooth and powerful V-6 and a slick, close-ratio six-speed. SLK has soared in my opinion.

The engine and tranny were new for 2001 and carry over for 2002. So does the fine handling and responsive steering of the diminutive fliptop. The brakes are amazing. The six-speed is superb, with precisely chosen gear ratios that allow the driver to wring out optimum performance or to cruise quietly on the freeway in six-gear overdrive.

The firm suspension, which comes equipped with Mercedes’ Electronic Stability System that helps control skids in case you get too sporty, permits flat cornering and good road feel without being too hard on the occupants.

There is some tire thump over rough surfaces and sharp raps from such things as freeway expansion joints, but it’s never akin to the buckboard rides of vintage sports cars.

Like all Mercedes cars, the body structure feels solid and well built. Standard equipment includes anti-lock brakes and side-impact airbags.

The retractable steel roof remains SLK’s signature element and a feature that strongly boosts its appeal. The folding top eliminates the security and maintenance hassles of cloth while allowing a full-fledged convertible experience. And with the top up, the cabin is as snug and secure as any coupe’s. Plus, it draws admiring crowds whenever it’s retracted or deployed.

SLK is no longer alone with this feature, with Lexus following Mercedes (as it often does) with a retractable roof for its new SC430 sports car. And the newly unveiled SL roadster, SLK’s big brother in the Benz lineup, loses its fabric roof in favor of a retractable hardtop.

Top up, the SLK is indeed cozy. Maybe a little too cozy, even claustrophobic. There’s enough legroom and headroom, but the two passengers will find there’s little room in here for anything else. Ditto for the trunk. Actually, the trunk has a decent amount of space with the top up, but that roof structure has to go somewhere. With the top down, trunk space shrinks from 12 cubic feet to just 5.

Compared with the rest of the sports-car run, SLK is a pricey number. Certainly, Mercedes’ strong reputation for quality is a major selling point. But the $45,790 price tag of th est car, although well equipped, did give me pause. Add the desirable AMG performance package, and the SLK quickly soars past $50,000. The SLK 230 Kompressor is about $5,000 less than the SLK 320.

Still, SLK has a unique personality, and with its performance gear straightened out, it can now run with the big dogs.