The game Assetto Corsa is on sale through the 4th at Steam. $8 for the base game and all(?) the additional tracks and cars (somewhere in there is a GT40 MK I).
store.steampowered.com
I haven't yet tried it, but the game has good ratings. It'll run on a PC or Mac and you can drive it with the arrow keys (or a steering wheel).
Save 80% on Assetto Corsa on Steam
Assetto Corsa v1.16 introduces the new "Laguna Seca" laser-scanned track, 7 new cars among which the eagerly awaited Alfa Romeo Giulia Quadrifoglio! Check the changelog for further info!
I haven't yet tried it, but the game has good ratings. It'll run on a PC or Mac and you can drive it with the arrow keys (or a steering wheel).
