From an interview in Paris Review:
BALLARD-
Well, before starting Crash, for example, in 1969, I staged an exhibition of crashed cars at the New Arts Laboratory in London—three crashed cars in a formal gallery ambience. The centerpiece was a crashed Pontiac from the last great tail-fin period. The whole exhibition illustrated a scene from my previous book, Atrocity Exhibition,* where my Travis hero stages a similarly despairing exhibition. What I was doing was testing my own hypotheses about the ambiguities that surround the car crash, ambiguities that are at the heart of the book. I hired a topless girl to interview people on closed-circuit tv. The violent and overexcited reaction of the guests at the opening party was a deliberate imaginative overload which I imposed upon them in order to test my own obsession. The subsequent damage inflicted on the cars during the month of the show—people splashed them with paint, tore off the wing mirrors—and at the opening party, where the topless girl was almost raped in the rear seat of the Pontiac (a scene straight from Crash itself), convinced me I should write Crash. The girl later wrote a damningly hostile review of the show in an underground paper.