Monster 7m 29s time for 650bhp ZL1 beats lots of insanely fast things
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So, what’s new?
Following the industry trend - driven by ever lower emissions and greater performance - Chevy has slotted a new eight-speed automatic transmission in place of the old six-cog auto changer into the Stingray (and its heavy V8 trucks).
But shunning the same trend to use a ZF gearbox and just run their own shift program, like half a dozen carmakers, GM has actually designed and built this unit - codenamed GM 8L90 - itself. And it’s a pretty tidy piece of kit, too. Despite having two more gears in the stack, the new box is several kilos lighter than the outgoing unit.
But I’ll bet its change times aren’t a patch on the best double clutch boxes…
Well, bet away. But you will lose almost every time. The GM box, which was benchmarked against the Porsche 911’s PDK, doesn’t just match that industry leading unit’s swapping times - it also beats some of them. Plus it shaves another tenth off the 0-60mph time and quarter mile.
That’s impressive - how does it drive?
The GM engineers have done their homework on this one. While you can swap the gears yourself with the paddles, if you just leave it in drive with the clever Performance Traction Management (PTM) engaged, it does a fine job of adding and subtracting gears itself according to the conditions.
On GM’s Milford Proving Ground - a tarmac greatest hits of all the most savage corners in the world, including one they call ‘Toilet Bowl’ - it quickly became clear that the eight-speed box makes an already great car even better, letting you concentrate on the track and enjoy the TG award-winning Stingray’s fine handling.
The box has another party trick worth noting on the track. If you just pull on the downshift paddle and hold it on the way into a corner, the car will shift to the lowest gear the computer reckons it can handle. It doesn’t sound like much, but when you are learning a new circuit it’s a great feature. When you get to a corner, you can brake then just pull on the lever and aim for the apex, then power out.
What’s it like on the road?
Pretty seamless. it never seems to be in a gear too high or low. Just instant response when you put your foot down. Likewise, it has none of the twin-clutch stutter coming out of junctions, so you can perfectly time your insertion into the traffic.
So is it better than the seven-speed manual?
For everyday road and track driving, yes. We’d completely understand if you chose the manual, though. It’s not an outstanding changer but it does give you that complete control you can’t get with any auto box.
When can I buy one?
The eight-speed auto box will be fitted to all 2015 model year Corvette Stingrays specified with an automatic. The same unit - plus a couple of coolers - will also be available in the new Z06 which debuts later this year. We can’t wait.