I'd make two full lists: driving games I like that need c2d, and horizontal games I like that need c2d. I'd rank the games by how much I like them, how much time I play, etc. Then compare the lists by total number of games, and how the games ranks against each other. From what the OP said, that's 3 driving games, and 4 horizontal games that need c2d, but little said on how they rank against each other.
I love driving games, but many of the racing games I really like are the top down, 360 degree wheel games. So... I'd stay horizontal, but only by a hair.