Convertibles for the open road

Whether you want to inject some fun into your daily driving, long to trade in the SUV for a good midlife-crisis car, or simply daydream of top-down driving on a sunny afternoon, it's hard to go wrong with a luxury roadster.

These convertible two-seat sports cars blend a fun-to-drive character, plenty of performance, lots of features, and striking looks that can turn heads on the road.

For this issue, we tested the Porsche Boxster, Mercedes-Benz SLK, Audi TT, and BMW Z4, which range in price from the TT's $45,300 to the Boxster's $59,600.

Of the four, the redesigned Boxster easily comes out ahead, with a score of 89. It handles, accelerates, and brakes with the best; it is relatively practical; and its soft- top is very easy to operate.

Although each model scores well in our testing, we can't recommend any of them because we don't have sufficient reliability data from our subscribers.

OK, reality check. Roadsters have their drawbacks in everyday driving. They don't have much cargo space, the seats are often tight and low, and the ride can be stiff. And if you're willing to give up some performance, features, refinement, and panache, you can get a Mazda Miata for about $15,000 to $30,000 less than these four.

The mid-engine Boxster delivers the purest sports-car experience of the four roadsters we tested. It's quick and agile, with an invigorating engine note. Braking is superlative. Turn-in response is telepathic, and the body stays even-keel. All of that makes it truly fun to drive.

The Boxster also has an impeccable interior, a tolerable ride, and a convertible top that operates with the press of a button and can be quickly raised or lowered while driving up to 31 mph. Thanks to a wind blocker, wind buffeting is minimal with the top down.

Our test car's 265-hp, 2.7-liter six-cylinder engine is paired with a crisp six-speed manual transmission. The Boxster might not feel as brawny as a Corvette from a standstill, but acceleration builds quickly. And it's smooth and returns a decent 23 mpg overall.

The mid-engine design allows for front and rear trunks, notable in a class where cargo space is piddling. Gripes include meager top-up rear visibility and some confusing controls.

Helped by its retractable hard-top, the SLK is the most luxurious of our four cars and the best for a long cruise. With the top up, it provides the enclosed quiet and comfort of a sports coupe. But the top can be folded away with the press of a button.

The SLK also shines for its sporty character. Handling is crisp and agile, with good steering feedback. At its handling limits, the stability control allows some tailslide, but the car is balanced and predictable. The SLK achieved a high speed through our avoidance maneuver but was a bit challenging to navigate through the cones. The ride is firm yet supple. And stopping distances are very short.

Though the 1.8-liter turbocharged engine in our SLK250 can sound a bit wheezy, it delivers plenty of thrust while getting an impressive 26 mpg overall. But the shifter and clutch action of the six-speed manual transmission makes it hard to drive smoothly.

The snug cabin is well finished, but the car's low stance makes access difficult.

The TT convertible is not only a nimble, fun-to-drive roadster but also one of the few convertibles available with all-wheel drive. That said, the summer tires in the S line package will need to be swapped for winter rubber if you plan to drive in snowy conditions.

Handling is sporty but less engaging than the Boxster's or SLK's. Stops are very short, but the stiff ride can be somewhat taxing. A lot of noise comes through the soft top. At its high handling limits, the TT showed tenacious cornering grip. It aced our avoidance maneuver, giving drivers a lot of confidence while they threaded the cones.

The 211-hp turbocharged four-cylinder engine is plenty punchy, sounds invigorating, and gets a respectable 25 mpg overall. The slick automated-manual transmission shifts quickly and smoothly.

Unlike the others here, the TT is relatively roomy inside and you don't feel like you're sitting on the ground. The cabin is nicely finished, with stylish details and comfortable but snug seats. Access is difficult.

The cloth top can be opened and closed at low speeds. But despite a wind blocker, there's quite a bit of wind buffeting with the top down.

Going by the numbers, the Z4 performs well, accelerating faster than many competitors. It also garners better fuel economy, an impressive 28 mpg overall from its 2.0-liter turbocharged four-cylinder engine.

Another big draw is the retractable hard-top. It operates slowly but keeps the cabin relatively quiet, compared with soft-top roadsters.

But the Z4 isn't as fun to drive as the others here. Braking is excellent, and handling is secure, but more body lean and a penchant for running wide when pushed makes it less engaging. The taut ride often becomes jarring. And the diesel-like clatter of the idling engine is not the purr that enthusiasts crave.

The six-speed manual transmission is precise but notchy; an eight-speed automatic is optional, as are two powerful six-cylinder engines that come with a seven-speed automated manual.

The interior is well finished, with firmly padded and supportive but very snug seats. And because you sit very low in the Z4, it's hard getting into the cabin.

The small trunk can hold only two duffel bags, but a shelf limits what you can put in when the top is down.