Pontiac expected to sell about 5,000. By the end of the 1964 model year, buyers had ordered 32,450 Tempests with the GTO package, a $295 option that put a big-car V8 into a mid-size body. It was not the first fast American car, and it was not the first big engine in a smaller car. But it was the one that sold, in numbers nobody at Pontiac had planned for. A Way Around the Rules…