GM 8L90 8-speed AT
The all-new, GM-developed Hydra-Matic 8L90 8-speed AT set to be mated to the FSP 6.2L V8 engine in the 2015 Chevrolet Silverado 1500 will provide improved efficiency over the current abysmal 15/21/17 mpg city/highway/combined rating. GM said it has 11 percent greater torque capacity than the current 6L80 6-speed automatic AT. The new AT uses four simple gearsets and five clutches (two brake clutches and three rotating clutches) within a tight package allowing the all-new 8-speed to fit the same space as the current 6-speed AT. It is not only lighter than the outgoing 6-speed AT, it incorporates a wider 7.0 overall ratio spread.