BMW’s new M DKG seven-speed double clutch transmission

Incomparably smooth, silky gearshifts in the blink of an eye, improved fuel economy and reduced emissions are just some of the benefits of the ground-breaking seven-speed M double-clutch transmission with Drivelogic that has been developed by BMW M GmbH for the new BMW M3 Coupé, Sedan and Convertible.

On top of these benefits, the new M double-clutch transmission with Drivelogic is able to produce lightning-fast gearshifts that result in accelerative abilities exceeding those of the six-speed manual transmission version of the new BMW M3.

The BMW M3 Coupé with M double-clutch transmission with Drivelogic is able to accelerate from zero to 100km/h in just 4.6 seconds, or 0.2 of a second faster than the manual six-speed version, while returning an average fuel consumption of 11.9 litres/100 km.

As the world’s first seven-speed double-clutch gearbox developed for a high-torque, high-speed powerplant, the new BMW M double-clutch transmission with Drivelogic simultaneously lifts refinement and efficiency to new levels while providing the driver with a wide range of options that adapt the system to the needs of the moment.

The new transmission offers as many as eleven driver-selectable electronically controlled driving program choices.

These include five shift programs in the fully automatic mode and six in manual mode, and are supplemented by a selectable Launch Control program that provides blistering off-the-line acceleration where the power from the 309 kW, 4.0-litre V8 M3 engine is transferred with maximum effect to the road.

The heart of the new BMW transmission is the double clutch system that acts to smooth out gearshifts to the point that they are often only discernible by watching the rise and fall of engine rpm on the M3’s tachometer.

Each oil-cooled wet clutch activates its own set of ratios - one is used for first, third, fifth and seventh gears, as well as reverse, while the other looks after second, fourth and sixth gears.

Gearshifts are effected by the disengagement of one clutch and the engagement of the other, moving seamlessly from the ratio in use to the next, preselected ratio.

The fact that the next ratio is preselected and engaged merely by activation of the clutch is the secret behind the amazingly smooth and efficient transition from gear to gear.

Combined with the BMW Drivelogic system that, as well as offering the driver a choice of seven specific operational modes, is also able to determine the appropriate mode according to the current driving style, the new transmission’s multi-faceted nature allows it to offer anything from rapid-fire F1-style shifting to smooth, luxurious behaviour suited to relaxed boulevard cruising.

The new M double-clutch transmission with Drivelogic also incorporates a Low Speed Assistant mode that operates when manoeuvring at speeds less than 5 km/h to significantly increase the smoothness and degree of accelerator control available to the driver.

Gradient detection also means that the new M double-clutch transmission with Drivelogic is able to determine the appropriate ratios when travelling up or down hills.

This avoids the “hunting” between gears so often experienced in regular automatics when travelling on undulating roads, while the appropriate selection of lower gears on downhill gradients helps maintain road speed by using the braking power of the engine.

The new M double-clutch transmission with Drivelogic also offers the driver the choice of sequential operation via a sports selector lever in the centre console, or solid aluminium F1-style paddles on the steering wheel - right side for upshifts, left side for downshifts.

The range of shift programs available to the driver means it is possible for the M3 to behave with the grace and aplomb of a luxury car, or with the knife-edge rapidity and precision of a racecar - or anything in between.

In fully automatic D mode, the driver can select from five Drivelogic programmes that regulate both the gearshift speeds and the change points right through to the D5 mode where the engine is stretched close to its maximum rpm - depending on throttle position - on upshifts. In D1 mode, the M3 with M double-clutch transmission with Drivelogic is able to start off in second gear to help avoid wheelspin in slippery conditions.

In manual mode, six different Drivelogic programmes allow a similar range of characteristics, with the added driver control provided by the ability to choose shift points manually. In S6 mode, the drive can also activate launch control by holding the shift lever in the forward position.

In keeping with the overtly dynamic abilities of the new BMW M3, the M double-clutch transmission with Drivelogic, as well as being designed for engine speeds as high as 9,000 rpm, is also able to maintain correct operating temperatures even in the most extreme conditions - including racetrack operation - through its integration with the engine’s cooling system as well as the fact it also incorporates its own oil/air cooler.

The transmission’s interconnection with the engine cooling system also means a quicker temperature rise from startup, which contributes to reduced frictional losses and lower fuel consumption during the warm-up phase.