Hardtop: Fourth-Gen BMW 3 Series Convertible Revealed Before Detroit Debut

MUNICH, Germany — If you can't beat 'em, match 'em.

After condemning the folding hardtops of rival carmakers, BMW has come up with one of its own for its new fourth-generation 3 Series convertible, pictured here officially for the first time ahead of the new German open-top's planned public premiere at the North American International Auto Show in Detroit in January.

Departing from tradition, the new 3 Series convertible eschews a fabric hood for an electronically controlled folding hardtop — a first for BMW. The decision is not without controversy; BMW had been particularly outspoken about the retractable arrangements of rival carmakers in recent times, suggesting they are unnecessarily heavy and serve to raise the center of gravity and thus compromise handling.

However, strong sales of folding-hardtop models in many of BMW's main markets seems to have led to a change of heart. Presumably the German carmaker's marketing department won out over the wishes of engineers.

Still, BMW cites a number of reasons for choosing the folding hardtop over a fabric hood, including added security and reduced noise levels brought on by the lightweight steel structure. It also says the design of the new 3 Series convertible's roof improves visibility because its rear window is 38 percent larger and rear side windows have 30 percent greater area than the windows of its predecessor.

The three-piece steel roof was developed with German specialist Edscha, the same company responsible for the fabric hood found on the 6 Series convertible and rumored to be involved in the development of the upcoming 1 Series convertible that is due out late next year. It can be lowered in just 22 seconds, either at the press of a button on the dashboard or optionally — for those who enjoy a little street theater — via the key fob up to a distance of 13 feet.

Stylistically, the new 3 Series convertible adheres closely to the recently introduced 3 Series coupe. BMW points to the way the new roof can be stowed in its own dedicated space behind the cabin without upsetting the characteristic low trunk line and rear-end styling. It also claims to have taken steps to ensure the windshield header rail does not intrude too close to front-seat occupants' heads, a criticism particular to some cars boasting a folding hardtop.

BMW has a wide range of engines for its new open-top, although only two, in the 325i and 335i, will be available at the time of the 3 Series convertible's North American launch in the spring. They range from a new 170-horsepower 2.0-liter four-cylinder featuring BMW's high-precision direct-injection system in the base 320i convertible all the way up to a powerful 306-hp twin-turbocharged 3.0-liter inline six-cylinder in the range-topping 335i convertible. The latter is claimed to go from zero to 62 mph in 5.8 seconds and achieve an electronically limited 155-mph top speed. Those figures place it on the same performance plane as Mercedes-Benz's CLK500 convertible.

Positioned between them is the 325i convertible's 2.5-liter inline six-cylinder pushing out 218 hp, and the 330i convertible's 3.0-liter inline six-cylinder with 272 hp. BMW is also planning to introduce a 330d convertible in Europe with its popular turbocharged 3.0-liter inline six-cylinder diesel engine offering up a sturdy 231 hp.

All models have a standard six-speed manual gearbox, with a six-speed automatic available as an option.

Despite the added weight brought on by the retractable hardtop, BMW is already making big claims about the new rear-wheel-drive 3 Series convertible's stiffness, saying it achieves the highest level of torsional rigidity ever seen in a convertible in its history. Among the weight-saving measures undertaken by Munich engineers is the incorporation of plastic panels at the front end, although BMW says curb weight is approximately 440 pounds over that of the 3 Series coupe.

What this means to you: It looks like the real deal and is likely to be more refined than any of its predecessors, but will the adoption of a folding-hardtop roof spoil the BMW 3 Series convertible's reputation as one of the best-handling open-top cars on the market?