Various oval cars:
Which is why www.tradingpaints.com exists; the new app synchronises your skin list.
I hope iRacing will take the skin support to the next level and do the syncing in game like Live For Speed. I know one reason they gave was legal complications but if LFS for example can do it then there has to be a way to do it. Its not a massively important feature but more of a 'feature plus' feature.
I dont think it will ever happen, They have already written to all world championship drivers to not use custom skins due to copyright reasons in the broadcasts. They got a telling off for having a skoal painted car in a screenshot on the Nascar.com website for the race reports or something like that.
Personally I would ask why did a member of staff at iRacing download the skins to take the screenshots for Nascar.com?... Surely it was iRacings mistake.