General Motors will replace most of its 6-speed automatic transmissions with newer, more efficient 9-speed units starting with some trims of the 2017 Chevrolet Malibu, the automaker announced Tuesday.
The outgoing 6-speed is used in a wide array of vehicles including the current Chevrolet Cruze, Equinox, Impala, Sonic, Traverse, and Trax; GMC Acadia and Terrain; Buick Enclave, Cascada, Encore, Envision, LaCrosse, and Regal; and Cadillac XTS. Some trims of the Chevrolet Malibu and Cadillac XT5 use an Aisin 8-speed automatic, and GM said it will replace the Malibu's 8-speed first.
2017 Chevrolet Malibu
According to GM, the incoming 9-speed will be roughly 3 percent more efficient on the Malibu 2.0-liter turbo-4 than the current 8-speed, which is made by Aisin. The 2016 Chevrolet Malibu 2.0-liter turbo-4 managed 22 mpg city, 32 highway, 26 combined, according to the EPA. The 2017 Malibu 2.0-liter turbo-4 with the new 9-speed automatic is rated at 22/33/26 mpg.
Those gains are incremental on paper, but GM engineers say the efficiency goes beyond EPA ratings.
Assistant Chief Engineer for the transmission Scott Kline said the new transmission adopts a new clutch system for first and reverse that improves lower-speed coasting in first gear, such as driving around a parking lot, and improves shift responses between gears with a new planetary gearset that works better than outgoing 6-speed automatics.
The new 9-speed has a wider gear ratio, including two overdrive gears, and a new clutch design that reduces the overall size of the transmission to fit into current cars equipped with the 6-speed automatic gearbox. GM engineers say the 9th gear, the most fuel efficient, would be used between 13 and 52 percent of the time, depending on the fuel economy test.
GM says the new 9-speed sports a newer engine stop-start that should restart the engines more smoothly and help acceleration. A deeper first gear ratio should provide those cars with quicker acceleration, GM engineers say.