Some years ago, Ford Motor Company and General Motors struck a deal to split costs and share engineering on a pair of fuel-efficient new automatic transmissions. One of those transmissions is a ten-speed automatic for longitudinal (RWD-based) vehicles like the Ford Mustang and Chevrolet Camaro, which has already found its way into a fairly wide range of Blue Oval products. Ford took the engineering lead on that transmission. The other is a GM-developed nine-speed intended for transverse (FWD-based) vehicles, which debuted in the 2017 Chevrolet Malibu Turbo before making its way into several other GM products.
But Ford has yet to use the nine-speed automatic transmission, despite having just revealed freshened-up versions of the Edge and Transit Connect. The reason? According to a recent article published by Automotive News, Ford didn’t see enough extra efficiency from the new transmission’s ninth gear to justify the extra cost and weight. Ford has instead come up with a pair of eight-speed automatics to serve in the GM transmission’s place.
Granted, one of those transmissions is based on GM’s nine-speed, with one forward drive ratio simply eliminated. The other, made for somewhat higher-performance vehicles like the new Ford Edge ST, is based on a six-speed developed as part of a 2002 Ford/GM partnership. Reportedly, a third eight-speed for lower-torque vehicles is in the pipeline.
According to AN, Ford made the decision not to use the GM-developed nine-speed transverse automatic as-is before GM ever put the transmission in a vehicle. When GM eventually did press the new gearbox into service, there was little to no efficiency gain over GM’s eight-speed. AN points out that the 2017 Chevrolet Malibu gained just 1 mpg on the highway over the previous car with the eight-speed, while the Buick Envision actually lost 1 mpg highway when it traded in its six-speed for the nine for 2019.
Comments
The assumption that more speeds equal greater efficiency is a fallacy. That fact is that a shift event is a period during which power is not transmitted fully to driving the vehicle but wasted as heat when one gear slips while the other is engaging. More steps planetary gear sets and clutches to spin around also results in high parasitic drag. These things offset efficiency gains from being closer to the optimal gearing more of the the time. Performance and refinement aside, efficiency gains from a transmission is largely obtained from having a wider ratio spread between the 1st gear and the tallest gear. If you can have a 5 or 6 speed automatic matching a 9 or 10 speed’s 7.6:1 ratio spread you’ll have similar or possibly slight better economy.
Yup but a 10 speed sounds cool