I’ve followed Super-Stock and then A-Street closely over the years. While I’ve never owned an A-Street car, I have co-driven in the class on occasion. A-Street and it’s predecessor Super-Stock have been two of our premier classes with interesting cars, compelling marque competition and they always draw top driving talent.
A-Street class has been dominated in recent years by the sixth-generation Corvette Z06 model (C6Z06), so much that people newer to the sport may think this is the way it’s always been. Prompted by comments from some of the old hands I did some investigation to see just how the class has gotten on since 2006, the first year of the C6Z06.
The first surprising thing that I found is that the C6Z06 never won its class (Super-Stock) at Nationals during its production years from 2006 to 2013. People ran the car during those years but it was beaten over and over again by the Porsche GT3, the Dodge Viper, the Lotus Elise and the C5Z06. For whatever reason, it looks to me like no really top-level driver drove it, either. I don’t know why, but I suspect that the perception was that it just wasn’t quite as good as the GT3, plus it was not cheap.
In 2010 the C6 Grandsport model was released and some top drivers, like Sam Strano, did give that car a try. The Grandsport never won, but Strano came in 2nd in 2011 to Braun in the Elise.
I don’t understand why people thought more of the Grandsport than the Z06. It’s gearing made it only equal to the C6Z06 in acceleration, at best. It weighed significantly more for the exact same rims and tires and the suspension was effectively softer. As a new car it was at best equal in cost (or more expensive) than an early C6Z06. By then the issue with the C6Z06 cylinder heads had become known, but the true extent, cause and the proper fix were not well understood. Maybe this issue kept some people away from the car. Or, maybe it was the generally-held opinion that it was a tricky, ill-handling car at the limit. Magazine testers constantly harped on that, but most of them don’t have the skills to consistently drive at the limit in any car that has good transient response, so I always discount their opinions about handling except for those who have a bone-fide high-performance driving background. I never had any issues at the limit with any C6Z06 that I’ve autocrossed, I can’t even recall ever spinning one, but they were all well-setup examples with expensive shocks, sticky tires and race alignments, all of which certainly create a departure from the stock condition.
2014 was the first year of Street on 200TW tires instead of Stock on DOT race composition tires and the classes were reconstituted. For the first time the C6Z06 was separated from the GT3 and Elise. The C6Z06 went into A-Street while the other two went into Super-Street and it won at Nats for the first time with Daddio at the wheel, one of the best-ever autocross drivers. C5Z06 cars were 2nd and 3rd, with an S2000CR in 4th. Compared to the “super-200” tires we have now, those first 200TW tires were really pretty bad. You just couldn’t use much power coming off a corner.
In the meantime the GT3 went on a tear in Super-Street, winning in 2014, 2015, 2016 and 2017. In 2018 a GT4 won. In 2019 the new NSX won.
Then in 2015 Yom won A-Street in a C5Z06, beating Daddio who was again driving the C6Z06. The next year Daddio won A-Street again in his C6Z06 with C5Z06 drivers taking 2nd and 3rd.
In another swap-around in 2017 Frank, in a C5Z06, beat Daddio in his C6Z06 to take the win in A-Street. Beginning to see a pattern? Or the lack of one?
In 2018 C5Z06 cars took 1st and 2nd with a C6Z06 in 3rd. In total, over the first 5 years of Street the C5Z06 won three times vs. two wins for the C6Z06.
It was not until 2019 that the tide began to change. C6Z06 cars took 1st and 2nd. A Cayman S took 3rd and a C5Z06 took 4th. This was the first time that a C5Z06 was not either 1st or 2nd in A-Street.
Nationals were not held in 2020 due to Covid. In 2021 C6Z06 cars took 1st (Charles Krampert in the car in the picture above), 2nd and 3rd. This was the first year you could say that the C6Z06 dominated A-Street, with Cayman GTS drivers in 4th and 5th. C5Z06s were 7th and 9th, driven by excellent but, I think most would say, at that point in time, somewhat lesser talents than some who had piloted that car in previous years, no disrespect intended. The C5Z06 may have finally lost favor, probably due more to the age of the car than any performance reason, except possibly for one thing.
In my estimation, the courses at National Tours have been getting faster, though perhaps not those at Nationals itself. Newer cars in almost all Street classes have been getting more powerful. They have also been getting heavier, but in general the power increases have outpaced the weight increases so acceleration performance has been improving. I think some course designers have been, perhaps unconsciously, catering to these higher power cars by setting up courses that have at least one location where more acceleration and thus a faster top speed than previously typical can be achieved. Sometimes more than one location. The C5Z06 tops out in 2nd gear at about 70mph. Up to that speed it’s a close match to the C6Z06 thanks to its gearing. But, if the course allows a higher top speed, the C6Z06 will continue to accelerate extremely quickly on up to 75mph, even 80mph. The C5Z06 is then at a marked disadvantage as the car either sits on the rev limiter or the driver is forced to upshift. It is rarely advantageous overall to upshift in such a situation unless you can really use 3rd gear for a while. That happens almost never, so it makes sense to now favor the C6 over the C5.
In 2022 C6Z06 drivers took 7 of 8 trophies in A-Street, with a C5Z06 in 5th. The best Cayman, the same car and driver that took 3rd in 2019, was 10th. Though the courses absolutely did not allow the Z06 to use its power advantage, grip ruled on both courses. C6Z06s have more grip than the Porsches, more grip than most anything else in Street, at least as measured by weight to total rim-width ratio. Plus they have a negative camber advantage over the Porsches on the front end, a wider track and probably a lower center of gravity, all things that tend to produce grip. It’s like that old saying, “There’s three things most important in autocross: grip, grip and grip.”
OK, maybe I made that up.