DETROIT – ZF Friedrichshafen AG is readying a second generation of its 6-speed automatic transmission with mechatronic enhancements that improve vehicle fuel economy by approximately 3% compared with its current 6-speed automatic, a ZF engineer says at this week’s Convergence 2006 Transportation Electronics Conference.

ZF was at the forefront of multi-speed automatic transmissions when it launched the 6-speed HP19, although subsequent new automatics have adopted seven and even eight forward gears. The primary advantage with more gears typically is a larger overall gear-ratio “spread,” which can improve fuel economy markedly.

ZF’s Harald Deiss says the company’s upcoming second-generation 6-speed automatic, the HP21, will incorporate “smart” electronic controls to optimize shift strategy.

The second-generation 6-speed automatic also incorporates a new mechanical damper system for the torque converter that “closes the clutch as soon as possible,” to hasten converter lockup in all gears. He does not say when the first HP21 production units will hit the road.

Deiss also says ZF plans to battle transmission competitors with an even more efficient automatic coming in about 2010. That transmission will generate another 5% fuel-economy gain by featuring more gears, a larger ratio spread, further optimized shift strategies and a special launch control.

bvisnic@wardsauto.com