With the SMG transmission of the E36 M3, for the first time a sequential transmission, which were popular in motorsports, entered the series. The system was a cooperative production of the BMW M GmbH together with Fichtel&Sachs and the transmission manufacturer Getrag. Unfortunately the transmission exposed to be quite vulnerable and unreliable. Several threads in online forums reveal experience reports from owners, who spent serious amounts of money in the repair. Remark: because of the low spread of this system and the high age of the model series, we offer neither spare parts nor information for the SMG I.
The second generation of the sequntial manual transmission developed by the BMW GmbH can be seen as the most famous and successful. The SMG II was created in cooperation with Getrag and the ZF Sachs AG and fitted exclusively to the BMW E46 M3. Also the SMG II bases on the normal manual transmission of the model series, the Getrag S6S420G. The probably most important change compared to the predecessor from the E36 M3 is the introduction of the Drive Logic System - an intelligent control, which adapts the shift characteristics of the transmission individually to each driving style. In the sport mode the system allows shifting times around 80ms and hereby a value, which is significantly below the shifting times of the Non-M SMGs. Furthermore the E46 M3 can be distinguished from the Non-M SMGs as the hydraulic components of the systems are located spread across the engine compartment. This simplifies maintenance procedures. Another difference can be find in the usage: in contrast to the Non-M SMGs, each shift paddle of the E46 M3 steering wheel is dedicated either for up- or downshift. The famous E46 M3 CSL was equipped only with the SMG II gearbox.
The SMG system developed by the BMW M GmbH for the E60 M5 and E63 M6 is the latest but also last generation. Distributed under the name SMG III, the sequential gearbox features 7 gears and promises 20% faster shifting times compared to the predecessor from the E46 M3. Also contrary to the predecessor, the hydraulic components of the SMG III are mounted on the transmission or even integrated inside the transmission body. Also the SMG III includes the already mentioned Drive Logic System
The 5-speed SMG was the first sequential transmission of the E46 model series. As gearbox basis the GS5S31BZ from ZF was used. The on the gearbox mounted, electro-hydraulic shifting system was developed by the italian automotive supplier Magneti Marelli. In contradiction to the SMG II from the E46 M3, all hydraulic components of the 5-speed SMG are mounted directly on the gearbox. The system offers an automatic ("D" on the instrument cluster) as well as an sport mode, which can be activated by a button next to the shift knob. Magneti Marelli distributed its system also under the name Selespeed. It was not only used for the BMW E46 model series, but also for various Alfa Romeo, Fiat, Ferrari und Maserati vehicles.
The 6-speed SMG was introduced in the production year 2002 for the E46 model series and superseeded hereby its 5-speed predecessor. Just a short time later the system was also offered for the Z4 E85, 6-series E63 and 5-series E60. At the E60 model series the used parts varied slightly depending on the engine size. The stronger engines (4,5 and 5 liter) were fitted for example with a fortified clutch actuator as it was used also in the E63-series. Also the 6-speed SMG offers a automatic as well as a sport mode. Technically the SMG is based on the respective manual transmission of each series - in case of the 3-series E46 for example on the Getrag GS6-37BZ. The hydraulic components are a construction of the ZF Sachs AG, however some parts were kept from the 5-speed SMG.