M3 V8 sans top

First Drive: 2008 BMW M3 Convertible

By Paul Horrell

Blazing toward 8400 rpm in sixth gear on an autobahn in a BMW M3 is already intense. Doing it in the brand-new Convertible -- roof down with a more direct sonic route from eight open throttles and four fat tailpipes to your ears -- is more intense still. Doing it with the brand-new M DCT double-clutch transmission, the shift lights blinking, just a finger-tap from an instantaneous (and we mean instantaneous) shift to seventh? Well, that's probably all the intensity most of us will ever need.

The new $2700 M DCT transmission doesn't just pack seven gears, it also has a science-lab's worth of electronic know-how and is the first such tranny that can cope with supercar levels of power and torque. Audi might promote DCTs, but its top-line R8 automated manual is still a rather clunky single-clutch mechanism.

BMW guys say their new DCT will even cope with the M5's 500 horses, but won't say whether a business case exists to replace the single-clutch SMG in the current M5 generation.

To make things easier for drivers who owned the previous-gen M3 with SMG, the interface of the DCT is exactly the same. You get a stubby "gearlever" (actually just a giant switch) with R and N on one plane, N in the middle, and +/- to the right. As in competition-car practice, it's forward for down, back for up. There are also steering-wheel paddles, nice firm metal jobs, with - on the left and + on the right.

Finally, a Drivelogic button controls the degree of aggression of the shifts and, in auto mode, the actual shift strategy. It runs from 1 to 5, plus a position 6 for launch control. So you get plenty of choice as to how the thing operates.

In D mode and set at level 1, upshifts are smooth and early. It's far preferable to the nodding-head effect of a conventional single-clutch AMT in this mode. Interestingly, though, it has not been set to creep in traffic -- you need to touch the throttle to get the car to move.

At the other extreme in manual mode and set to level 5, you actually get shift shock, as this harnesses the rotational inertia of the engine as it sheds revs, propelling you forward and helping make a 0-62-mph time of 5.1 seconds. That's 0.2 quicker than the six-speed manual. During downshifts in levels 4 and 5, it blips the throttle explosively and addictively.

Oh, and having seven ratios also marginally helps the DCT's fuel-consumption numbers by about two mpg compared with the manual.

But is this the optimum M3? Trouble is the Convertible weighs 510 pounds more than the Coupe, and so with the same transmission gives away a half second in the 0-to-62 sprint. Sure you get an enhanced feeling of speed with the roof down, but then there are body-rigidity issues. Handling is still fabulous, but feel through the steering is lost.

Sure you can drive with the roof up, in which case refinement and rigidity pretty much rise to coupe levels, but you're still carrying the extra mass and so you are dulling that most precious M3 asset, the blinding punch.

For the ultimate driver's 3 Series, go for an M3 Coupe or sedan with DCT, we say.