Pointed out originally and discussed here: http://isiforums.net/f/showthread.php/27437-ISI-OPEN-Servers-2-Race-GTs-Safety-car The Open server 2 uses v1.47 of the SLS Merc and getmod doesn't work and v1.44 is the latest version on the download site. I'm using a non-Steam version. Apparently Steam Workshop has the v1.47 version. But according to the details it's v1.43 though it's been updated once on the 10th still remaining as v1.43.
Believe this has been resolved. If still not working for you, you can now download v1.47 from the launcher's remote content window (I did that last night).