BMW’s New Double-Clutch Tranny: Ours Goes to Seven

BMW’s version of the double-clutch transmission--an idea pioneered by Volkswagen/Audi and Borg Warner--gets seven speeds and a U.S. debut in May in the new M3 Convertible, BMW execs confirmed at a national press drive for the new sportscar.

BMW’s “Double Clutch Gearbox” is also the only gearbox of its kind designed specifically for high-powered engines, the company says.

In the U.S., the new transmission will be an M3 exclusive for the near future. After the DCG arrives in the Convertible, it’ll spread to the M3 sedan and coupe later in the summer.

BMW’s spin on double-clutch technology gives M3 drivers an alternative to the standard six-speed manual available on the vehicle--and effectively replaces BMW’s old SMG transmission, which was roundly criticized by enthusiast mags for its shift quality in past editions of the M car lineup.

Like similar transmissions, the DCG uses twin sets of clutches to engage gears sequentially, so that there is little to no perceptible shift lag. Effectively two transmissions in one, double-clutch gearboxes also can improve acceleration times (by up to 0.2 seconds in the M3) and in BMW’s case, fuel efficiency as well. It can be shifted in manual mode (though there is no clutch pedal), or left in a drive mode to shift automatically.

The DCG will sport a console-mounted shift lever and a set of shift paddles on the steering column. It will also be twinned with Drivelogic software, which sets five separate shift programs in “D” automatic mode, and six shift programs in “S” manual mode, which in turn allows the driver to choose a quicker shift response or a smoother one, for example.

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