List custom posts on user page in admin area.

I have a custom member site in the works and I’m not the savviest coder out here. (but I love to learn) My first question (of many to come) is how can I associate custom posts with certain WP users? For example: the site will have members (standard WP users). The site will also have a listing of, say, cars. The car listings are custom post types and have various specific data associate with them (color, make, model etc). I want to be able to have a listing of all available cars show up on my user pages in the backend and be able to associate all applicable cars to that user. I then would need to output that data to the front-end of the site via get_usermeta() (or similar custom function).

I realize this is a complicated question but any suggestions, tips or shoves in the right direction would be greatly appreciated.

thanks, Shag