The guys over at ISI have just released a new build of their famous rFactor 2 game.
This is the first official 64bit release, the launcher will automatically start 64bit if the system is compatible (you can run 32bit by going to the advanced tab and checking the box to run 32bit instead).
Due to file system changes to accommodate the 32bit and 64bit files and folders, a CLEAN INSTALL is highly recommended to avoid orphaned files or duplicate files. Auto update should not have these issues at all. Advice on clean installs can be found linked from the news item above.