First drive: M-DCT improves BMW's mad M3 breed
BY DAVID HASSALL | 19th Jun 2008
The Bavarian company claims this is the first dual-clutch transmission developed to handle a true high-performance engine as it arrives here just before the similar seven-speed PDK automated manual in the facelifted Porsche 911.
BMW’s new dual-clutch gearbox will first arrive in the M3 Coupe as a $6900 option, with deliveries starting in July - two months before the Porsche arrives here.
However, while M3 Convertible demonstration models will also be in BMW dealerships from next month, potential owners will have to wait until at least the last quarter of this year before deliveries commence – just in time for summer.
BMW will not confirm pricing until closer to launch, but has targeted a figure of $169,000 – $12,000 more than the M3 Coupe that was launched here in October last year – and the company expects to sell up to 150 here in the first year.
It has also confirmed that Australia's first M3 sedan will arrive here around the same time as the convertible, with an anticipated price of around $145,000 – $12,000 less than the two-door coupe and about $24,000 less than the forthcoming convertible.
Of course, the four-seat M3 Convertible loses the coupe’s signature carbon -fibre roof, but features all the other M3 styling cues - including the aluminium bonnet with power bulge, flared wheel-arches, air-intake gills in the front side panels, 18-inch wheels and rear air-dam with diffuser, punctuated by dual M tailpipes.
It also features the same three-setting adaptive sports suspension, cross-drilled braking and electronic dynamic drive systems as the M3 Coupe, making it one of the sportiest convertibles in the world.
It also features the ‘SunReflective’ leather upholstery developed by BMW for its motorcycles, which keeps the upholstery up to 20 degrees cooler than conventional leather when parked in the sun.
Otherwise, only the doors, bootlid, windows, tail-lights and automatically activating rollover protection bars behind the rear seats are interchangeable between the 3 Series Convertible and the M3 Convertible.
Power comes from the same 4.0-litre V8 engine producing 309kW at 8300rpm and 400Nm of torque at 3900rpm, driving through a standard ZF six-speed manual or the optional new seven-speed M-DCT gearbox.
Although the engine is 15kg lighter than the previous six-cylinder unit, the M3’s overall weight is up by 100kg. However, with more than 100 horsepower per litre from the V8, its power-to-weight ratio is considerably improved over the 56kW-less-powerful E46 generation, making the latest M3 Convertible the fastest yet.
Fitted with the fast-changing DCT transmission, the new M3 Convertible will accelerate from rest to 100km/h in 5.1 seconds, but the standard manual gearbox model is a little slower at 5.3 – which is 0.2 sseconds faster than the six-cylinder E46 but some 0.5 slower than the M3 Coupe.
As well as being faster, the new V8 is more economical and cleaner than the six-cylinder, with an official Australian combined fuel consumption figure of 12.9L/100km for the manual and only 12.3L/100km for the dual-clutch version.
BMW Australia marketing manager Tom Noble said that the new M3 Convertible with the M-DCT gearbox will be as close as any of its customers will get to driving its Formula One car (which last week scored its first Grand Prix victory).
“The M3 Convertible is a sublime product and one of the best from BMW M. It will be hugely satisfying for both our existing M3 Convertible owners as well as newcomers to the BMW M brand,” he said.
“The M3 Convertible will appeal to buyers who want to combine the performance and peerless engineering of a traditional M car with the unique driving experience of an open-top car.
“With its vast array of new technology and Formula One-inspired engineering – including the option of the new seven speed double-clutch transmission – the M3 Convertible’s appeal is wider than ever. It’s as close as a BMW owner can get to a Formula One experience.
“We are sure the introduction of the retractable hard-top will broaden the M3 Convertible’s potential customer base. With its coupe-matching refinement, excellent visibility and improved practicality, the convertible will be on the shopping lists of many who may have eschewed a canvas roof car previously.” The new seven-speed double-clutch gearbox was developed specifically for the M3 with German transmission specialist Getrag in Germany and is a major step forward from BMW’s previous single-clutch SMG (sequential-manual gearbox) units that first appeared in 1996 in the M3.
M3 drivers will be able to manually flatshift (without lifting the throttle) using either steering wheel paddles or the central gearshift, with BMW claiming seamless shifting and no interruption in power delivery.
Of course, dual-clutch transmissions are nothing new and are even available in humble VW Golfs, but developing a unit to handle high revs and massive torque outputs was quite another challenge.
The DCT effectively combines two gearboxes in one assembly that is no bigger than a conventional unit, yet contains two oil-cooled clutches – one controlling the even-numbered gears and other controlling the odd-numbered gears and reverse.
When driving, one of the two clutches is always engaged and, when accelerating or shifting down, the clutches are activated in an alternating fashion. An electronic control unit assesses which ratio is going to be the next required and pre-selects it, leaving the clutch open.
As soon as the driver activates the gearshift, it is instantly engaged. This entire process is completed faster than the time it takes a driver to depress the clutch pedal with the standard six-speed manual.
In full automatic mode, BMW’s ‘Drivelogic’ control system provides five driving programs so the driver can select the shift characteristics (speed and revs) while a preferred setting can be stored and then recalled instantly by pressing a button on the steering wheel.
Like the previous SMG transmission, the DCT has a launch control function that allows the fastest possible acceleration away from standstill at the push of a button.
To assist manual shifting, a strip of eight LED shift lights incorporated into the upper edge of the rev counter – six yellow and two red – light up as the engine revs rise, with all eight lighting up simultaneously at the redline.
Drive impressions:
WHEN a company like BMW commits to a new technology, you can expect results, and our first taste of its new dual-clutch gearbox indicates that the Bavarian company has got it right.While the previous single-clutch SMG gearbox had its faults, especially with snatchy shifts in auto mode around town, the new DCT has proved itself to be just as impressive trundling around town in auto mode as it is in manual ‘race’ mode on a tight and demanding mountain pass.
Launched to the Australian media installed in the new convertible version of the awesome V8-engined M3, the DCG is a stunning piece of engineering and comes with so many electronic controls that it can be configured to suit just about any driver in any circumstance.
Better still, you do not need to scroll through the still-daunting BMW iDrive controller to find the setting you want, just press a few simple buttons on the steering wheel and centre console.
Leave it in ‘auto’ mode and you can select one of five ‘Drivetronic’ shift regimes – from slow to sharp – simply by pressing a rocker switch just in front of the gearshift, or push the M button on the steering wheel for an instant transformation into racing car mode with barking mad manual shifts that punch you in the back on upshifts and blip the throttle on downshifts.
Driving away from the lights can be a little awkward in auto, with an initial throttle delay and then a surge of power, but just select the slightly misleading ‘Power’ button next to your left leg and suddenly the throttle becomes more responsive, allowing a smoother getaway.
It might all sound slightly daunting, but in reality it is nothing of the sort. The controls are clear to see and fall easily to hand, and after a while behind the wheel playing around with the options you quickly work out what works for you.
And what really worked for us was the one-touch M mode on the aforementioned and blissfully clear mountain road west of Port Macquarie, where the M3 Convertible won our hearts with a spirited yet supremely comfortable and controlled blast, accompanied by the aural delights of the brilliant 4.0-litre V8, howling at the top of its rev range and snarling in appreciation as you brake hard and snap down a couple of gears for the hairpins. You couldn’t wipe the smile off my face.
After running like that, the auto mode just felt sluggish by comparison, even in the sportiest setting. Around town, though, we would have no problem trundling around letting the DCT make all the decisions.
While we are not fans of convertibles in general – why would you want to add weight and ruin a perfectly good chassis by hacking off the roof for the questionable upside of getting wet, burnt and windblown? – the M3 made us think again. But only for a moment.
Then we considered how good the M3 Coupe will be with the DCG, but without the considerable 230kg weight penalty from having a steel (rather than carbon-fibre) roof, a bunch of electric motors and extra reinforcement beams to keep it from twisting like a pretzel.
That 230kg of weight is like carrying three big blokes in the car with you, and that makes quite a difference, especially at lower speeds.
It would be foolish to describe a car that accelerates to 100km/h in 5.1 seconds as sluggish, but consider that the coupe with the same transmission will be half a second faster again.
The car’s party trick is launch control, which involves a fairly convoluted series of actions – select Drive, disengage the stability control, select the launch setting, push the lever forward and hold it, mash the throttle, let the lever go – and then you race away with neck-snapping upshifts. But who needs it? We also loved the feel of the steering, but what really surprised us was the M3’s ride quality, given the handling capabilities it possesses and the big, aggressive tyres it wears. It certainly felt better than a humble 323i with run-flat tyres.
Those big Michelins no doubt contributed to the considerable roar we suffered on the coarse bitumen roads in the hills, but they had no trouble dealing with the various bumps and undulations along the way with considerable poise and comfort – even with the electronic dampers turned to their sportiest setting.
Apart from road noise and the extra weight, our biggest quibble with the M3 Convertible – apart from the regular 3 Series Convertible issues like rear seat and boot space and, of course, the iDrive – is that the standard-size brake pedal is to the right of centre near the throttle, which makes left-foot braking a bit tricky.
Otherwise, it’s every bit as impressive as you would expect from a $170,000 BMW. But if we could afford one, we’d take the M3 Coupe and pocket the change without hesitation.