CSR Racing is an amazingly realistic racing game for Windows and best of all, its completely free.
CSR Racing features stunning graphics and addictive gameplay with a range of high performance cars including Audi R8, BMW M3 and Chevy Corvette. You can even customize them with turbos, nitrous injection and aerodynamic tweaks to make them go even faster.
Other cars to chose from include Ford, GM, Mini and Nissan, Audi R8, Ford GT, Chevrolet Camaro, Nissan and GT-R. You can upgrade these with turbos, racing tires and much more although you have to get the balance right - give your car too thin tyres with too many turbos and it'll be out of whack! The aim of the game is territory - beat the gangs and the gang leaders to take over their side of the city until you own it all.
CSR Racing might not be as big as commercial racing games but for free, it's an excellent racing sim.