http://www.carfax.com/car_buying/vin_cloning.cfx - If you are looking to buy a used car, then a VIN lookup is necessary. Simply find the VIN of the car and do a V.I.N. search. You can even look for a free check VIN service online so you do not have to pay to get the history of the used car you are interested in. If you do a VIN check you can avoid the lemons and duds.