BMW has announced the introduction of its new seven-speed, semi-automatic transmission.Using dual-clutch technology similar to that on Volkswagen's DSG gearbox, the BMW 'M double-clutch transmission' (M DCT) is the first transmission to mate dual-clutch technology with a seven-speed 'box. Using two clutches means that the next gear is already engaged before you select it. The BMW 'box uses one clutch for the even numbers (2,4,6) and the other for odd numbers and reverse (1,3,5,7). As you change gear, one clutch disengages at virtually the same time as the other engages, allowing for smoother and faster gearchanges.The M DCT is teamed with BMW's familiar 'Drivelogic' system, which allows eleven different settings – five in automatic mode and six in manual, when the driver can shift cogs using the F1-style paddles or the gear stick.Official figures show that the new gearbox gets the M3 coupé to 62mph in 4.6sec – 0.2sec faster than the standard six-speed manual model.Other benefits include improved fuel economy and better control for low speed manoeuvres thanks to a 'Low Speed Assist' setting; changes that will be more relevant to many buyers than better acceleration. M DCT will debut as an option priced at around £2500 on the M3 cabriolet, so we'll have to wait until the drop-top V8's launch later this year for the official verdict. Until then, have a look at the stunning new M3 cabriolet by clicking here.