I liked the race modifications in GT1 and GT2, it kept it competetive and challenging with how much cash you had on hand, but did tend to get annoying after a while. It did make you become a manager in a sense, you had to keep track of how much money you were spending on new cars and modifications and plan ahead a little.
Also with the Veyron, it would be a real disapointment for a car like that with such high expectations and a lofty name to turn out to handle like a pig in the game (and in real life for that matter).