Dubbed 9G-Tronic, the gearbox will offer improved fuel efficiency and reduced CO2 emissions compared to the existing seven-speed 7G-Tronic. It will be mated to large displacement engines and could make a possible debut on the redesigned 2012 S-Class. Going forward, Mercedes apparently believes that nine gears is the maximum number of ratios that are technically possible. More importantly, the company thinks consumers won't accept a ten-speed unit. It may be too complex to build one as well.
The 7G-Tronic was the first seven-speed automatic transmission when it was introduced in 2003. In recent years, it has been outclassed by the new 8-speed ZF transmission used by Audi and BMW.