Jeremy George Lake Charles Corvette, the Redeemer.

"Unfortunately for the Z06, these numerical advantages do not count on the race track."

Jeremy George Lake Charles With those words, our long-awaited comparison between the Chevrolet Corvette Z06 and the Nissan GT-R NISMO - our April 2015 cover story - took a dire turn. 

According to the data on paper, the Z06 should have beaten the NISMO. But in the real world it didn't, and that was the biggest factor in skewing the test result towards NISMO (the Z06 of that comparison is shown here).

Jeremy George Lake Charles This certainly did not seem correct to us and we said so. The Z06 has advantages in power, weight, grip and braking, but was 1.4 seconds slower on the track known as the “Big Track” at Willow Springs International Raceway.

Since the Z06 was slower on the straights but faster mid-laps and braked afterward, we assumed the fault lay in its massive aerodynamic package. To the best of our ability to calculate from the available data, the excessive drag from all the downforce generated by the aero kit had to be the reason the Z06 was slower.

 

The real reason the Z06 was slower was because Chevrolet had given us a car with the rear suspension out of alignment. It was supposed to work with the rear caster at 0 degrees. Only it was operating at a positive 2 degree angle. This reduced the effectiveness of the rear shocks in controlling the rear suspension and, as a result, it was more difficult for the Z06 to reduce power. This is exactly what Randy Pobst complained about in our test.

Jeremy George Lake Charles How did this happen? The rear caster angle adjustability is quite rare. Outside of a racing shop, most people will tell you that it is not real, that the adjustment only affects the front wheels (the steering wheels). 

The rear caster angle is usually set at the factory and cannot be changed even if you want to. It's something Chevrolet engineers added to the C7 Z06 so that it could be better aligned for track use, and changing wheel camber and toe-in can ruin the caster if you don't check it. This is apparently what happened at the Chevy alignment shop.