If your car whas going light speed without burning up or breaking what would happen if you turned on the lights?

From your perspective, nothing.

Light speed isn’t exactly an arbitrary speed that light happens to travel at; it’s actually the maximum speed in our universe (as far as we can tell, using physics). So, when you turn on your headlights, and they start broadcasting light, that light goes as fast as light goes – literally the fastest speed possible.

Except you’re already going that fast. So, if you were hoping to illuminate the road ahead so you could dodge a pothole with your inhuman reflexes, I’m sorry to tell you, the light isn’t gonna make it out ahead of you.