According to a recent report, Mercedes is developing a nine-speed automatic transmission.
Dubbed 9G-Tronic, the gearbox will offer improved fuel efficiency and reduced CO2 emissions compared to the seven-speed 7G-Tronic. It will be used on large displacement engines and possibly debut on the redesigned 2012 S-Class.
Going forward, Mercedes apparently believes 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.
As you may recall, 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.