My original comment (above) was posted in the FM7 Technical Support section of the forums in the hope of the matter getting some attention- a Moderator redirected it here where it is guaranteed to get no attention!
I have since sent a private message to SOY (Community Liaison) about FM4 Car Club and FM3 Storefront issues with no reply as of yet
Xbox360 games will be lower on their list of priorities but hopefully a fix will happen eventually
It would certainly be nice if car clubs on FM4 worked again, especially even just for the sake of getting a few easy achievements that are otherwise stupidly unobtainable!