As I understand it, Grundy will not cover your car unless it is damaged going to, at, or leaving a show or parade.
As for Progressive... I have one word: "****". They are overpriced and take forever to pay out claims.
I use GMAC for my Buick since USAA won't cover it. I pay about $80 a month for comp / collision with decent limits here in Las Vegas. I'm also 27 with a squeaky clean record, so that makes a difference.
Peter