iseecars.com
iSeeCars runs free VIN-based analytics on top of live US listing data. Enter a VIN or browse a model to get a deal rating (great / good / fair / overpriced) benchmarked against comparable cars, projected depreciation and 5-year cost of ownership, expected days-on-market, and price-drop history. A useful sanity check on whether a US asking price is fair before you negotiate.
United States