About a year ago, General Motors introduced their 6T40 6-speed automatic transmission. It was built for small and mid-sized car market and promised to boost fuel economy by 5%. Since then the engineers at GM have been working on ways to improve upon the already solid gearbox, the results of which have yielded another 5% boost in overall economy.
The updated version of the 6T40 is based on the lessons learned while designing the drivetrain for the new Chevy Equinox. By redesigning the internal electronic control systems, such as changing the shift points, another 3% jump in fuel economy was recorded.
The other 2% came from gutting and rebuilding the internal components of the transmission. By replacing the hydraulic valve body with a more efficient unit and altering the friction plates to match, the overall losses from pump pressure and friction were reduced. Less friction and negative pressure means more power gets to the ground.
Alongside the new 6T40 transmission, GM is developing a dual clutch gearbox to use in later applications to boost economy even more, though no timeline has been announced.