A nine speed automatic gearbox is the idea from Mercedes-Benz to pull up one notch higher in the continuing and ongoing race for the best in the automobile market. Cars from them that would be fitted with large capacity engines would have this feature, as the latest reports from the company so revealed.
The cliché about the six speed auto gear box has come from Autocar who in turn have got it from a senior source in Mercedes Benz. They have also stated that this new gear box design would have a good cascading effect on the fuel economy and CO2 emissions of the car. Audi, BMW and Lexus which are the closest rivals to Mercedes Benz already have cars with eight sped gear boxes and some of them even with dual clutch units that are much faster.
The reason Mercedes-Benz is going for a nine sped automatic even though the dual clutch transmission systems have been known to give lots of fuel efficiency is due to the reason that automatic gear system are lighter and more reliable as well as cheaper to manufacture than the dual clutch systems.
Technically speaking nine ratios is the max number possible and therefore Mercedes Benz would not go for any more number of gear mechanisms. As it is adding just one more gear itself is going to be a technically trying task. In addition, a nine gear setup is perhaps the highest that customers would not be able to cope up with.
Confirmation from Mercedes to all these speculations is yet awaited.
Source: motorauthority