I just got a new 2006 Prius and they tried to sell me a bunch of extras which I did not buy. I live in Roanoke, VA, where it does snow occasionally, and we do get a lot of freezing rain as well, so they do salt the roads in the winter. (In fact, we got about 6 inches yesterday). Do I need to buy the protective undercoating or not? They were going to charge about $350 at the dealer, which I didn't think was terribly high.