An oldy but a goody for Porsche only:
https://en.wikipedia.org/wiki/Need_for_Speed%3A_Porsche_Unleashed.
Great graphics for it's time, first-person driving, and a basic arcade feel which makes it easy to drive.
Another oldy:
https://en.wikipedia.org/wiki/GT_Legends
A little more simulation, huge car selection, and almost all the tracks.
(Actually, on second thought....those may be a bit too advanced and challenging for a 9yo. It should be fun not stressful.)
Something like fun feedback learning might give him more satisfaction:
Sheppard Software: Fun free online learning games and activities for kids.