Toyota and powertrain specialist Aisin are working on automatic transmissions with "more than seven" speeds, according to Automotive News Europe (ANE).

Independently, the two companies admitted that their research has led to transmission systems with more ratios than those seen on current production models. Today, the seven-speed Mercedes-Benz 7G-tronic is the automatic transmission with the greatest number of ratios. On its high-performance M5 sedan, BMW offers a seven-speed sequential-manual transmission.

Previously, the 6HP series from German transmission specialist ZF introduced the six speed automatic in 2001. It is offered on BMW, Jaguar and other luxury models.

Toyota is "looking at automatics with more speeds, especially for the premium market," Kazuhiko Miyadera, R&D executive vice president at Toyota Motor Engineering and Manufacturing Europe said in an interview.

Miyadera did not specify how many speeds the transmissions under study would have. Miyadera declined to say when such transmissions might make it to market. Separately, Japan-based Aisin Warner - Toyota's principal transmission supplier - also hinted it is looking at increasing the number of ratios in its gearboxes.

"Mercedes and ZF both have seven speeds already," testing engineer Bertram Kurz said in an interview. "So there would be little point in us only doing that."

More speeds in an automatic transmission allow a greater spread of ratios and a taller top gear for more economical cruising. And the smaller steps between ratios would give smoother upshifts and downshifts.