All engine versions of the new sports sedan are specified as standard with a state-of-the-art six-speed manual transmission. Alternatively, an eight-speed automatic transmission is optionally available. Both transmissions boast optimised efficiency, compact design and reduced weight. In the BMW 335i and the two diesel versions, the six-speed manual transmission features dry sump lubrication and a modified gear train design. This new design reduces drag losses in the gear train, while oil supply management largely eliminates churning. All versions with manual transmission are also equipped with an Optimum Shift Indicator which shows the driver the ideal moment to change gear, taking into account the current driving situation. When the new ECO PRO mode is activated, the recommendations in this display are always geared to maximised fuel efficiency.

The eight-speed automatic transmission likewise features innovative gearing design. Although this new unit is neither larger nor heavier than the previous six-speed automatic, it offers two additional ratios and a larger overall ratio spread. Together with the minimised torque converter slip, high internal efficiency, low friction losses and intelligent transmission control, this creates substantial potential for fuel savings. The BMW 335i, BMW 328i and BMW 320d actually achieve better standard EU fuel consumption with this transmission than with the manual version, while compared with the previous six-speed automatic transmission, fuel consumption has been improved by between 9 and 13 per cent. Even the low-CO2 BMW 320d EfficientDynamics Edition achieves just as good fuel consumption and emissions with this transmission as with a manual unit. The new ECO PRO mode programmes the transmission to bring forward upshifts and to delay downshifts.