Camaroboy makes a good point: GT5rologue was released pretty much exactly three years before GT5. Prologue featured 6 HD tracks and about 70 cars of GT5 premium standard in a well-working game. So what the hell did they do in those three years after that? Also, Kaz admitted that they went a bit overboard with the level of detail of the premium cars. A more realistic planning would probably have brought us a much bigger number of cars.