It seems working now. (Mon July 13, 10:43 Pacific).
One thing I noticed is that the range is capped to 100 miles. An unlimited range would be incredibly useful for searching for used exotics, i.e. Ferraris, which is a valid input parameter :-). Since supply (both overall and for a particular configuration) is so limited, it makes sense to buyers to fly to see the car or to buy blind and ship the car to them.
This will be added very soon. In the meantime, if you change "distance=100" in the url to "distance=all" you can search all results -- although in some cases we dont allow this (like if you havent select a make) as it is pretty intensive on the server when we have a lot of results to return.
We have done similar search engine for Turkish used car ad sites. It has been really fun to build such a thing since there are number of things to compensate and normalize data collected from various sources. I have learned a lot while doing it.
http://techcrunch.com/2012/10/01/facebook-acqhires-founders-...