MILFORD, Michigan -- Here’s the thing about driving a 2015 Chevrolet Corvette Stingray around the Milford Road Course at General Motors Proving Ground: It’s hard. The car is blistering fast, and the course is incredibly tight -- 2.9 miles of blind corners, hills, and chicanes, with practically no straightaway. We have enough to worry about without ever thinking about shifting. Good thing we don’t have to: This 2015 Chevrolet Corvette is equipped with an eight-speed automatic.
Automatics are nothing new to Corvettes, of course. The car debuted in 1953 with a two-speed Powerglide, and two-thirds of Corvettes sold these days have two pedals. GM’s new eight-speed, however, essentially erases any remaining performance gap with the stick shift. It hits 60 mph in 3.7 seconds, a tenth of a second faster than what GM achieves with the seven-speed manual. The transmission weighs about the same as the old six-speed automatic, which means it’s still heavier than the manual gearbox. It’s also a bit heavier than a comparable ZF eight-speed automatic, which GM engineers attribute to the fact that their new transmission must stand up to towing in full-size trucks. It also will have to handle the 650 lb-ft of torque produced by the upcoming 2015 Chevrolet Corvette Z06. The Corvette team says it passed on a dual-clutch automatic because it needs the high-torque capacity, and must spread the cost of transmission development by sharing it with the high-volume trucks.
Despite its torque converter, the new eight-speed shifts very fast -- faster than some dual-clutch transmissions -- GM says. Full-throttle shifts have that near-instantaneous quality we’ve come to associate with Porsches, only here, the soundtrack is of a mighty 460-hp V-8 ripping through gears. Even more impressive is the transmission’s performance on the track, where the shift logic is unimpeachable. We just put it in drive and go, and let the software figure out where and when to downshift for us. At times, we can feel some hesitation as various computers and sensors -- in the engine, the transmission, the active differential, the dampers, the brakes, etc. -- figure out exactly how much power to deliver to the rear wheels. But we’ve observed the same sensation in manual transmission cars, which are nearly as computerized.
Later, we hit the highway for a fuel economy test. The additional gears, coupled with a slightly lower axle ratio, improve fuel economy from the ’14 C7 six-speed automatic’s 16/28 mpg by 1 mpg highway, to an EPA-rated 16/29 mpg. The seven-speed manual is rated 17/29 mpg. Corvette chief engineer Tadge Juechter notes the eight-speed’s highway mileage is actually within a whisker of 29.5 mpg and suspects his team will find a way to round up to the coveted 30 mpg rating next year. Cool. We worry more about testing 50 to 90 mph acceleration and thus see 14.1 mpg during 40 miles of mostly highway driving. The transmission quickly serves up full throttle downshifts except when you’re in Eco mode, where you must wait an additional split-second as deactivated cylinders come back online. Eco mode is also quicker to return the transmission to a higher gear.
In manual mode, the transmission responds quickly and immediately to driver commands, including multi-gear downshifts. The paddles themselves feel cheap and flimsy -- yes, they’re in the manual transmission cars as well, but are rarely used, as they toggle on and off the auto rev-matching feature. The Corvette team should hit up Cadillac for the magnesium paddles used in the ATS.
We do miss the manual at times -- like when we press the imaginary clutch to execute a heel-to-toe downshift on an exit ramp -- but the Corvette assaults the senses in so many ways that losing one input doesn’t ruin the experience.
2015 Chevrolet Corvette Stingray
|Price as Tested:||$65,680|
|Power:||460 hp @ 6000 rpm|
|Torque:||465 lb-ft @ 4600 rpm|
|Fuel economy:||16/29 city/hwy|
|0 to 60 mph:||3.7 seconds|