I'm sorry but I really can't see a scientist playing video games. Especially a racing game.
Wow! What a presumption. I am sure you'll find plenty of scientist, doctors, real life racers and professionals playing gt5. Also exorcet's physics is right.
Don't need to take his or my word for it. Read it up. Weight is not a major factor in straight-line flat surface top speed for vehicle with round tires. For animals running on legs(which I suppose u could be extrapolating from) it is big factor but not applicable to most vehicle without tracks. And, yes, car magazines written for entertainment sometimes adds to the confusion as they may use speed and acceleration interchangeably.