Toyota Motor Corp. and powertrain specialist Aisin Seiki Co. are working on automatic transmissions with more than seven speeds.
Independently, the companies admitted their research has led to transmission systems with more ratios than those seen on current models.
Today, the seven-speed Mercedes-Benz 7G-tronic is the automatic transmission with the largest number of gear ratios. BMW offers a seven-speed sequential-manual transmission on its high-performance M5 sedan.
Before that, ZF Friedrichshafen AG introduced its 6HP series six-speed automatic. It is offered on BMW, Jaguar and other luxury models.
Toyota is "looking at automatics with more speeds," said Kazuhiko Miyadera, executive vice president at Toyota Motor Engineering & Manufacturing Europe. He did not specify how many speeds the transmissions under study would have, but he said: "Maybe a little bit more than seven. It would give us more suitable gear ratios and more fuel efficiency. And I've already driven them."
Miyadera declined to say when such transmissions might make it to market.
Separately, Aisin Seiki unit Aisin Warner also hinted that it's looking at increasing the number of ratios in its gearboxes. "Mercedes and ZF both have seven speeds already," said Bertram Kurz, a testing engineer. "So there would be little point in us only doing that."