CAR drives M3 Convertible with BMW Dual-Clutch Gearbox (M-DCT)
http://www.carmagazine.co.uk/D...M-DCT/
The BMW M3 Convertible is not a Footballers’ Wives kind of car. The convertible M3 might be heavier and bendier than the coupe but, along with that glorious V8, this car also hasa surprise up its sleeve in the form of BMW’s new double-clutch semi-auto gearbox. Other M3s will be offered this transmission in time, but our first opportunity to try it is on this car.
So it’s BMW’s DSG for the M3 Convertible?
Yes, but BMW calls it M-DCT (double-clutch transmission) and, unlike the Volkswagen Group system thatcurrently only works on transverse engine applications, this one works with the M3’s longitudinal drivetrain. Like the older, simpler, single-clutch SMG 'box fitted to the M5 and M6, this one has seven forward ratios, an auto mode and a launch control function.
But unlike the SMG, is it any good?
Better than that, it’s one of the best dual-clutch transmissions we’ve tried. Changes are far smoother than they are in the older SMG, slurring through when you’re ambling and punching home with a jolt if you select the fastest shift speed and use all 8400rpm between changes.
But the throttle response is disappointingly soft unless you press the Power button on the centre console, and it can become confused when coming down the gears, particularly between first and second in slow traffic. There’s still a clunkiness to stop-start maneuvers too, say when making a three-point turn, that you don’t get with a proper auto. But, once moving, the M-DCT does a great impression of an auto-box – though no production auto could withstand the high rpm capability of the M3’s 414bhp V8.
What about the rest of the car? Does the convertible shell ruin the M3 experience?
When I first drove this generation of BMW convertible at the launch in Phoenix, small wheels did their utmost to disguise the loss of chassis stiffness. CAR’s long-term 335i Convertible on big rims has never felt quite so tidy. And neither does this M3. We’re not talking about scuttle-shake so bad that it renders the rear-view mirror redundant but, with the roof down, you can certainly feel movement that doesn’t occur in the coupe.
That said, the roof is very quiet in operation and, when stowed, allows you to hear so much more of the M3’s V8. And, with it in place, you could almost be persuaded to believe that you are in the closed car. It doesn’t look as neat as the coupe and there’s a slight but still perceptible performance penalty, 0-62mph taking 4.8sec in a manual M3 coupe and 5.3sec in a manual cabrio, although the M-DCT drops that to 5.1sec, squeezes an extra mile from every gallon of fuel and reduces CO2 to less than 300g/km.
But for the most part this still feels very much like an M3. So it’s stable, has a surprising amount of traction, and steadfastly refuses to understeer, even in the wet. But the steering, though still terrifically accurate despite the loss of the roof, suffers from the same lack of feel as do the saloon and coupe.
Verdict
Predictably, if you’re more interested in doorhandling than catching rays, the coupe is still the preferred choice. The loss of performance and rigidity here is certainly noticeable. But then you’re compensated by a very clever roof and the chance to really hear that V8 in all its unmuffled glory. As before, you’ll want one or the other but not both.
The M-DCT will divide opinion too. City drivers will love the two-pedal layout and improved smoothness over the SMG but the £2590 premium will be too much for many who still enjoy exercising their left legs. But fix the low-speed jerkiness and we’d find it hard not to recommend this new gearbox.
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Originally Posted by Iawa
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