But these incremental gains are becoming insignificant. According to Caspari, the company’s current eight-speed automatic transmission is only eleven percent more efficient than its six-speed automatic transmission.
Currently, many luxury automakers are using versions of ZF’s eight-speed, including BMW across its model range and Chrysler uses them for their 300 sedan. Chrysler is also planning to use a nine-speed automatic transmission for its upcoming Chrysler 200 and Dodge Avenger midsize sedan replacement.
Some time last year, Hyundai announced that they are developing a ten-speed automatic transmission which they planned to use on future versions of the Genesis, Equus and also probably the Kia K9 (which shares similar mechanical parts).
If a ten-speed automatic transmission does arrive, what’s next? Heading to an eleven, twelve or any higher number transmission could add cost and complexity without any realised gains in fuel efficiency that automakers are searching for as they prepare for mounting Corporate Average Fuel Economy (CAFE) regulations from the US federal government which is set to go up to 54.5 mpg by 2025.
Eventually, one day all of this will come to an end and automakers might go down the route of continuous variable auto transmissions (CVT), just like Nissan in most of its models. Instead of using a fixed number of gears, the Nissan transmission uses a chain-link belt that shuffles across two cone-shaped pulleys to give a nearly infinite variability, instead of fixed gears.
The gear-adding race is expected to come to an end soon or at least it will tone down a little. With Hyundai and ZF still in the midst of developing transmission with more gears, this race might go on for another decade or so. Anyway, soon is, after all, a relative word.