Originally Posted by RobertJ

Ziebart uses a process and chemical that coats these areas that aren't so finished from the factory. But if left outside, you're still going to have the problem with the drains getting gunked up and have water standing where you don't want it to. This is particularly bad where they use salt and you get a nice spray of salt water in these areas with no where for it to go. The Ziebart process will slow this down, and they do offer some sort of rust through warranty. How they stand by that warranty I don't know, but it may be worth looking into if you plan on keeping the car for very long.

The good news is that cars have come a long way and typically the drainage is much better and galvenized sheet metal is more rust resistant and used much more than in past years. If you plan on keepnig the car for only 5 or 6 years you'll probably be fine even parking it outside.