Revealing mistake: In the scene when Christine smashed repeatedly into the silver Camaro at the gas station, there is no motor in the Camaro. The hood of the Camaro gets knocked off the hinges and is twisted sideways on the car. As Christine is in reverse and dragging the Camaro along you can see down through the hood that the engine compartment is empty. Minus a transmission also, I believe. (01:15:30)
Revealing mistake: Whenever Christine is shown burning rubber, the thick, white smoke can be seen coming from somewhere up inside the wheel well, and when sprayed onto the spinning tire makes it appear that the tire is producing far more smoke than it actually is.
Chosen answer: Hydraulics and wires were set up inside the body to pull the panels in and crumple them. Then the film of this happening was simply run backwards.
Grumpy Scot