Thanks for the tip BigMeat. I really like the way it auto-pulls pics from CraigsList ads and displays them as thumbnails in the results list. But it doesn't seem very comprehensive to me. For example, because all it provides is a pre-populated dropdown, I can only search for "Isuzu Vehicross" - meaning anything listed under only Vehicross wouldn't show. The site also only seems to list vehicles in the results set, and many of them are repeated (whereas Google removes duplicative entries by default). I see you can also search by parts, but it only retrieves 9 total results. For comparison, when I search MashUp for Isuzu Vehicross I get 99 vehicle and part results from eBay and CraigsList combined. When I search those sites independently I get 2,095 eBay results and 84 CL results. The only reason the CL result count was that low was that I filtered on posting dates of Apr 1st or later, which is another option MashUp doesn't seem to offer.
Maybe I'm just using it wrong? Seems like a much better interface than SearchTempest, but not as thorough.