2015 Corvette Stingray 8-Speed Automatic Shifts Like A Rifle: First Drive

Bang. A twitch of the upshift tab on the 2015 Corvette Stingray jolts me into the seat bolsters.

Bang. Third gear now. A blink, a shift.

Bang. Fourth gear. Triple-digit speeds. All eyes forward.

And there are still four more gears to go.

The 2015 Corvette Stingray features incremental updates from last year’s model, introducing much of the hardware that will also be featured on the forthcoming 2015 Z06. For instance, the all-new 8L90 automatic transmission is preset for the 650 pound-feet of torque that the upcoming Z06 will turn at the crank, which means the 465 pound-feet in the base Stingray is a breeze for the many cogs. The seven-speed manual was also updated, with a faster, smoother Active Rev Matching system that can downshift faster than GM’s best performance drivers can heel-toe. Then there’s the innovative Performance Data Recorder, which stands at the crossroads between racing and social media.

The packaging of the 8L90 is also identical to that of the old six-speed unit, and the eight-speed weighs less, despite the added equipment within the housing. No double-clutch gearbox on the market today could fit in such a package envelope. This is thanks to the clever use of magnesium and aluminum, as well as lighter high-strength low alloy steel. The outgoing 6L80 featured no magnesium, and was 30 percent more parasitic than this new unit. The 8L90 also features an industry-first, chain-driven binary vane-type pump located within the valve body. This setup effectively allows for two pumps in the packaging size of one, which contributes to lower parasitic losses and optimal priming capability, as well as ideal oil routing to the controls system. There is a “high output” mode geared for performance, while the “low output” mode is for towards fuel economy. The overall gear ratio is 7.0 and the first gear ratio is a very aggressive 4.56.

There’s far more to dive into in regards to GM’s new eight-speed transmission, which will also be found in trucks and SUV models equipped with the 6.2L V8 motor (at first). But what you need to know is that the transmission results in an EPA estimated 29 miles per gallon on the highway, 16 mpg city and 20 mpg combined. The 30 mpg mark is said to have been missed by 0.1 miles per gallon. The Corvette team also hinted that they’re looking to go back next year, maybe with some added air in the tires or something, and try again for the 30 mpg mark. Still, no other non-hybrid car can compare to the 2015 Corvette’s combination of 460 horsepower, 0-60 mph in less than 3.7 seconds, and 29 mpg on the highway.

Driving on public roads mustered a better-than-anticipated 26.8 miles per gallon. This included some stop-and-go traffic, an on-ramp launch, and normal highway cruising of 70 mph in Eco mode. Despite the buttoned-up behavior, shifting still remained sharp. The graphic below illustrates some of the shifting times for the 8L90 compared to Porsche and its DCT, as well as the 2014 Corvette with with the six-speed automatic.

On the same end, the 2015 Stingray’s 0-60 performance is 0.1-second quicker than the 2014’s and its six-speed automatic, contributing to a quicker quarter-mile elapsed time of 11.9 seconds, also a 0.1-second improvement over the 6L80.

But as we’ve seen plenty of times before, the numbers game on paper is not where the battle is won. The Corvette team offered up a small pack of new 8L90-equipped Stingrays to drive around the incredibly challenging Milford Road Course — a crucible for all of GM’s performance cars. There is virtually no part of the track that straightens out, aside from the home straight which was coned off for safety reasons. In other words, there’s always some sort of turn, sweeper, embankment or elevation change happening. GM’s vehicle dynamics engineers who drive this asphalt roller coaster every day usually have about a G force of pressure on the car through the whole lap. I tried my best to match.

For the sake of the demonstration, I let the Stingray shift itself to see how well it computed, putting the car in Track, with the Sport 1 traction setting. And with a chirp of the wheels and the unmistakable growl of the LT1 V8, I fired into turn 1.

The trick to get the transmission to know its on a track is to be heavy on the throttle and braking. Otherwise, the computers may revert to thinking it’s cruising on the highway. It doesn’t matter what driving mode you’re in: when driven properly, the transmission kicks into the lowest gear possible at the current speed. When braking heavily, it will instinctively drop as much as three gears. And it will hold the RPMs when the throttle is steady around a turn. If the driver does things right, the transmission will, too. The video below will give you an auditory and visual example of how the transmission behaves when in D and in track conditions, as well as an impression of how fast the 8L90 shifts.

Like a gun. That’s how.