C3 headlights (and the wiper door on early cars) open and close using engine vacuum. Cracked hoses, leaking actuators, a failing control valve or a leaking reservoir make the doors slow, stuck or droop open over time. It's a system of many small parts, so leaks are common.

Some C7 Z06 owners, especially with early cars on hot days, report the car reducing power or showing high temperature warnings after a few hard laps. The supercharged LT4 creates a lot of heat. GM made changes to later cars, and the aftermarket offers cooling upgrades.