Ellen, The King Joe by Yakima would fit your PT Cruiser. I know that Yakima has great customer service. Here's a link: http://www.bikerackshops.com/YA026KINGJOE.html.

You can find fit guides for the major brands at http://www.bikerackshops.com/fit_guides.html.

To avoid damage to your Cruiser's finish, be sure to keep both the car and the strap rack feet as clean as possible. Have fun traveling with your bikes!