The combination of NASCAR and rFactor is a rather confusing story. It looks as every other week, a new NASCAR mod surfaces while we already have more than you could shake a stick at. NASCAR Sim Series throw themselves in the ring with their new 3.3 version.
The mod is based on the COT model by the Superspeedway.net mod for NASCAR 2003. This is a good base to start with as the model is rather good looking, even though NR2003 is not the newest sim anymore. The mod comes with all 2008 NASCAR Sprint Cup teams, representing all four manufacturers. The mod also comes with 22 tracks of varying quality, all wrapped in a nice menu system with good looking loading screen and such.
This is certainly one of the better NASCAR mods for rFactor, those of you looking for a high quality COT should wait for the final TPSCC version though.
