Here's one for Delenns husband. :) It's not a Need for Speed, Gran Turismo or Dirt but for free it's not bad. It's open source and improving all the time.
Speed Dreams (287Mb)
Speed Dreams is a Motorsport Simulator featuring high-quality 3D graphics and an accurate physics engine, all targeting maximum realism. Initially forked from TORCS, it has now reached a clearly higher realism level in visual and physics simulation, thanks to its active development team and growing community. It mainly aims to implement exciting new features, cars, tracks and AI opponents to make a more enjoyable game for the player, while constantly pushing forward visual and physics realism. It is also intended for any research, study or teaching activity, around physics and AI, thanks to its GPL V2+ license, and the clear and modular architecture of its C/C++ code base.
Video:
http://www.youtube.com/watch?feature=player_embedded&v=Wd4Kmu--PYA
Download:
You can download the latest version of Speed Dreams from source Forge or Desura, the latter requires you to have the desura client installed. The advantage being you will easily be able to update the game or install any mods that may arise from the game. The sourceforge download is HERE and the desura download HERE