For "car guys" you need to allow searching by the platform code. Way more important and specific than the decade-spanning model names. For example "e30" should return '83-91 BMW 3 Series.
Love that you can specify Slushbox/Manual and exclude salvage titles.
Very annoying that middle-clicking car posting titles on the 'grid view' page does not open the cars in new tabs. I want to scan through the list and open all the ones I find interesting, then look through the details one at a time.
Clicking the site's logo (top left) should bring you back to the no-current-search homepage. Not edit the current search. Right now it feels as if you can't entirely clear the search. Clicking back to the homepage should definitely do that.
I use this site for a list of desirable year/model cars. You might get a few ideas from them: http://autoemu.com/