The British premium automobile manufacturer MINI highlights the sporty character of its current models in the small segment with a new type of transmission. Extremely fast gear changes, a high degree of shift comfort and optimised efficiency – these are the benefits of the 7- speed Steptronic automatic transmission with double clutch, available for the MINI 3 door, the MINI 5 door and the MINI Convertible. It is offered in conjunction with selected engine types and as an alternative to the standard 6-speed manual transmission. The new double clutch transmission provides impressive shift dynamics for enhanced driving fun while at the same including all the comfort features of an automatic transmission.
The double clutch transmission is operated by means of a newly designed electronic selector lever which always returns to its original position after changing between driving mode D, neutral position N and reverse mode. The parking lock is activated by pressing the P button. S mode can be activated from position D by shifting the selector lever to the left: this supports a particularly sporty driving style as well as allowing manual intervention in the choice of position. The electronic control of the new double clutch transmission for MINI also includes a shift strategy based on navigation data and supports both the engine start/stop function and coasting so as to reduce fuel consumption and emission levels.
The design principle of the double clutch transmission has been adapted directly from motor racing. Just like on the race track, it allows MINI drivers to undertake highly dynamic acceleration manoeuvres by enabling upward gearshifts without torque interrupt. The driver can keep the accelerator pressed down while the transmission control sets the shift points so precisely within just a fraction of a second that the ideal engine speed is always available after the gearshift to ensure a continuous increase in speed.
This is possible due to the specific structure of the double clutch transmission. It combines two partial transmissions in a single housing. The core element of the system consists of two oil-cooled wet clutches: one of these is responsible for the even transmission ratios (2, 4, 6) while the other is for the uneven ratios (1, 3, 5, 7) and reverse. During travel, one of the two clutches is open and the other is closed. They interact when the driver shifts up or down: opening one clutch activates closure of the second at the same time.
If the MINI is accelerated in third gear, for example, power transmission occurs by means of the relevant clutch and the partial gear for the uneven transmission ratios. At the same time, the transmission control ensures that the next gear required – in this case fourth gear – is already engaged in the partial transmission responsible for the even transmission ratios. All that needs to be done to shift up is to open the clutch of the third gear and close that of the fourth gear. This happens simultaneously without any interruption of pulling power – and if anything takes less time than it would to activate the clutch pedal when driving with manual transmission.