Eight Should Oughta Do It: 2015 Corvette Stingray Gets Eight-Speed Auto

2015 Chevrolet Corvette Stingray

As you’ve probably read, the 2014 Corvette Stingray is pretty, um, awesome! Except for one thing: the optional six-speed automatic is a gear or two behind the times. To be truly competitive with other self-shifting sports cars of its caliber (and raise its fuel efficiency), it needs at least one more cog.

As has been widely expected, Chevrolet is adding that extra cog, and then another one on top of that, when it makes its new 8L90 eight-speed transmission available on the Stingray for the 2015 model year. Designed and built by GM, this same paddle-shifted transmission is based on the same design that will serve as the sole offering in the upcoming Z06, with four gear sets, five clutches, and torque-converter specifications matched to the naturally aspirated LT1’s 455 horsepower and 460 lb-ft of torque. Less space between ratios should allow drivers to make the most of the engine’s meaty powerband, although GM didn’t say if the gear spread is significantly broader than that of the outgoing six-speed.

GM has said that it couldn’t fit a dual-clutch unit in the same space in the Z06, but was nonetheless able to package this new tranny in the same rear axle location as the outgoing six-speed unit, technically making this a transaxle. GM further states that extensive use of aluminum and magnesium make the 8L90 more than eight pounds lighter than the six-speed, with reduced friction contributing to about 5 percent greater fuel efficiency.

2015 Hydra-Matic 8L90 (M5U) Eight-Speed RWD Auto TransaxleGM claims that the eight-speed automatic’s shift performance rivals that of the dual-clutch transmissions found in many supercars without the attendant drivability issues, with the transmission controller analyzing and executing commands 160 times per second. Wide-open throttle upshifts, for example, are executed up to eight-hundredths of a second quicker than those of the PDK dual-clutch transmission offered in the Porsche 911, according to GM.

Feature: In-Depth with the 2015 Chevrolet Corvette Z06
Comparison Test: 2014 Chevy Corvette Stingray Z51 vs. 2014 Porsche 911 Carrera S
Instrumented Test: 2014 Chevrolet Camaro Z/28

Whether or not the Vette’s new eight speed can outsmart the brilliant dual-clutches in its competitive set, we won’t know until we try it ourselves, but suffice it to say we probably won’t miss the six-speed. And if we don’t like it at all, there’s always the fine seven-speed manual, which we hope never goes away.
Eight Should Oughta Do It: 2015 Corvette Stingray Gets Eight-Speed Auto Photo Gallery

About Steve Siler