One member reported to me via PM that he wasn't able to rate Cars or Circuits on his iPhone (iOS 6). I've tested this myself on my iPhone running iOS 6 and the rating widgets were not working for me either. I tried it on my iPad (iOS 7) and my laptop (Windows 7), and it's working fine on both.
Before I post an issue with the module developer, I'd like to get more feedback from the community. For those of you with devices and OSs that are different from what has already been tried (as stated above), please try the rating widget for either Cars or Circuits and report back here.
Thanks in advance.