Checked integrity with steam several times. All files verified. Read several post here on forums, learned how to create a trace file. Looked at trace file and it says basically that it is starting in 32 bit mode and crashing because it surpasses the memory limitation of 32 bit mode. How do I start the game in 64 bit mode?
What operating system are you running. What are your system specs. Which version of rF2 are you using. A bit more info might be needed to give assistance.
After clicking play in Steam, rF2 syncronizes with Steam before displaying the rF2 launcher screen. Several Icons are on the left, clik on the circular icon that looks like a gear. You should then get the video config page. Near the upper right is a box that will be checked if you are in 32bit. Uncheck that. btw, the Nascar mod you are trying to run seems to have multiple issues of it's own. While still on that screen, open the video settings box and verify that your correct video card is displayed. Now click ok and try to launch rF2 again. Good Luck.