GM is launching the six-speeds in nearly 40 GM models around the world in 2006 and 2007. By 2010, the company plans a total of 10 new variants of the six-speed design, with annual production reaching three million units.
The first six-speed model, the Hydra-Matic 6L80 (shown at right), debuted in on GM's 2006 performance models and full-size SUVs, and the investment announcement coincides with the launch of its second six-speed variant, the 6L50, which will debut in 2007 Cadillac STS rear- and all-wheel drive sedans, and in the SRX V8 crossover.
Compared to a four-speed automatic, the new six-speeds provide both better performance (through a lower first gear) and better highway fuel economy (via two overdrive gears).
The 6L50 also features "Driver Shift Control," which allows the driver to shift the transmission like a clutchless manual 'box. Another nifty feature is transmission calibration to override automatic gear selection during closed-throttle and high lateral acceleration maneuvers (think aggressive corner entry), rapidly downshifting with nearly synchronous engine speed for quick power-up when the driver comes back on the throttle.