I never fold my dress shirts when transporting them. I just don't like the idea of folding. I use cloth bags instead to cover my dress shirts and hang them in the car if I need be.
Just in case I need to fold a dress shirt like, for example, returning it to the store because it was a size larger than the usual, or I need one for a trip abroad, the video below from Real Simple is a nifty how-to for this problem.
There is also an easy step-by-step photo tutorial of the video that can serve as an alternative. Still, I'd rather have you watch the video.