Assetto Corsa is really good if still unpolished, Dirt 3 is not bad good fun, Race 07 with its expansions, F1 2013 is also really good even tho the AI bugs the hell out of me, Many need for speed games you could also get Raceroom as its free to play on steam, GTR 2 is still fantastic, R Factor is a modding god, Or R Factor 2, Game Stock Car Extreme, Grid 1&2 also the upcomming Grid autosport. And if you have the time IRacing.