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BMW M3 Convertible M DCT
February 2, 2009
It’s an old debate. One that’s seen bare-knuckled brawls break out at braais and car forums degenerate into a ‘mine’s-bigger-than-yours’ contest with every second post asserting that ‘My M3 is better than your C63’, or ‘My Merc’s better than your Beemer’, or even ‘My forearm is bigger than your thigh’. Well, you get my point. Purists believe that if car doesn’t have three pedals or is not driven by the rear wheels, it’s not worthy of performance icon status. But the gap between front/all-wheel drive and rear wheel drive is getting smaller by the day. Compare the awe-inspiring S3 and the 130i Sport, for instance. Which would you rather have in your garage?
I’m a rear-wheel man by birth, but even I’ve had to admit in recent years that the choice is largely dependent on the models under consideration. In reality, there is little to choose between the various drivetrains in different environments.
The same can be said for the gap between automatics and manuals. It’s all a question of personal preference and the details execution of a specific model. No flappy paddle auto has ever offered me the same amount of control as a manual, especially on track, but double clutch automatics such as Audi’s S-tronic (previously DSG), Porsche’s PDK and BMW’s new M DCT are rapidly changing people’s perceptions.Debates raged for days after our June issue comparison test between Audi’s outgoing RS4, the new C63 and the manual M3. Two out of three of our testers eventually agreed that the AMG had a marginally better breadth of talents than the others over the 1800km evaluation. Yet there was little doubt that the Bavarian was always going to be the most convincing package on track. At the time we also said that the BMW’s DCT transmission would probably give us a more definitive answer when it arrived and would present more direct competition for Merc’s C63 than the manual M3.
Well, it’s arrived, and in convertible form nogal. Cabriolets by nature lose structural rigidity when the roof is lobbed off, and more weight is added to the chassis to reduce flex until a performance compromise is reached. But the M3 Cabriolet uses the clever three-piece electrohydraulic retractable hardtop from the 3-Series convertible – and that platform impressed us when we first drove it as its chassis is far stiffer than one would expect. On track, you’d be hard pressed to detect any dynamic difference between the hard top M3 and its cabriolet cousin with the top up. Expect the same sharp bite on turn-in, excellent mid-corner balance, high grip levels and fluent athleticism.
More at issue here is how the M DCT works than its wrapper. Significantly it’s the first double clutch transmission that can handle the high revving power of the Bavarian V8. Like the systems from other manufacturers, as one set of gears engages the even gears, the other set engages the odds. The electronic controller then predicts the next required ratio, releases one clutch and engages the other, resulting in fewer interruptions in power flow as cogs are swapped.
I had driven all three iterations of BMW’s Sequential Manual Gearbox (SMG) and each was as unconvincing as its predecessor. The SMG made it hard, if not impossible, to modulate throttle inputs and progress at low speeds. You would be barely touching the accelerator while trying to creep forward in traffic (or into your garage at home), and suddenly a surge of power would lunge you forwards, leaving you scrambling for the brake pedal. To ‘fix’ this, M division desensitised the throttle to such a degree that it now feels lethargic and lazy.The M DCT is idiot proof, but not ideal, mainly because the accelerator has to be pushed almost halfway through its travel to get any reasonable forward momentum. Every time I started up the cabrio, I had to press the Power button and adjust the Drivelogic function just to find a happy medium. I never got truly comfortable with the M DCT, finding its slow clutch engagement quite disconcerting. It exhibits a jerkiness during stop-start manoeuvres, and on track it hesitates, as if confused, on the occasional downshift. That said, it’s better than the SMG and on less aggressive settings shifts are so seamless you often miss them. Against the clock, we were also impressed with the acceleration times possible using M DCT, particularly as the cabrio is 205kg heavier than it’s hard-top sibling – at 163.9kW/tonne a 20kW/tonne power-to-weight shortfall. With the aid of its launch control system we achieved a 0-100km/h time only 0.01sec slower than the manual. BMW claims the M DCT is ‘comparably faster from 0 to 100 km/h by 0.2 seconds than the manual version’, but our results found the difference negligible.
So is this the ultimate performance solution? We’d say it’s close, but still no cigar and likely to add more fuel to braai-side debates. There’s no denying it’s a lot easier to live with than the SMG or the three-pedal version of the M3, but I would still prefer the six-speed manual for the track. The new box also commands a R39 000 premium over the manual. Even so, if BMW remedies its low-speed laziness, I’d find it hard not to recommend. -
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