How did this happen? Rear caster adjustability is pretty rare. Outside of a race shop, most people will tell you it's not a real thing, that caster adjustment only affects the front wheels (the steering wheels). Usually, rear caster is set at the factory and can't be changed even if you want to. It's something Chevrolet engineers added to the C7 Z06 so it could be better aligned for track duty, and when you change the rear camber and toe, you can mess up the caster if you don't check for it. This is apparently what happened at Chevy's alignment shop. Let's answer the obvious question then: How does the Z06 perform when the rear end is aligned properly? Better. Much better. Recall the car previously did a good-but-not-great 1:27.10 during our comparison test. This time? 1:25.00. A massive 2.1-second difference.