Lemonfree is a very interesting "used cars for sale" site, that hosts several related classifieds and that helps you find exactly what you are looking for.
You get to search by the car make, model, year, country (currently U.S. and Canada only) and Province /State /Region. Personally, I like the easy design and search method used, that doesn't get you lost like most other classified ads site. I think the guys did a great job, and I highly recommend their site if you plan on purchasing a good used car. Some of the deals they have are very competitive in prices and worth a look.
Some of the sections/ car models listed in the site include:
BMW 3 Series
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