DSG or the Direct Shift Gearbox is an electronically controlled multiple-shaft dual clutch gearshift used extensively by the Volkswagen family of cars. Basically, it is two manual gear boxes housed in one casing, so two clutches get rid of the Torque Converter and the shift timings are reduced considerably.
It was originally devised by BorgWarner (U.S. automotive parts supplier), later licensed to Volkswagen which tweaked it to get even better results. Initially only available with the FWD cars, later development has led to the DSG being used on the longitudinally mounted front engined Audis’ as well.
Working:- The basic outline are the two clutch sets of which the outer set drives the odd gears (1,3,5) and the reverse whereas the inner does the job for the even gears (2,4,6). So when a gear is changed, all it does is jump to the other clutch set (even to odd, or vice-versa) which helps in reducing the change times to milliseconds.
The entire range of Volkswagen family has been using the DSG’s rite from the Audi, VV, Seat, Skoda but an exception is the Bugatti Veyron which also uses a similar tech but developed by Ricardo (a UK based high performance parts manufacturer)
Along with the paddle shifts, the DSG has many advantages apart from fast shift times. No power is lost in the process due to the absence of the Torque Converter and so the fuel economy is also enhanced.