It's illegal in every state in the United States, but odometer fraud, one of the oldest tricks in the books, is on the increase and now has even gone high-tech, according to industry experts. Many people think digital odometers are not susceptible to being rolled back, but according to the experts all it takes is the right software and hardware to make the odometer read whatever number a scam artist wants. A number of foreign Web sites now market equipment to roll back digital odometers. And, although the fine print says these products shouldn't be used for unlawful purposes, more and more dishonest used-car salesmen do so to falsely inflate the value of a car, according to Carfax. This fraud also increases the chances the used-car buyer will have to pay for expensive repairs. Automotive experts say the best way consumers can protect themselves against hidden problems when purchasing a used car is to do their homework. Carfax.com says it has more than a billion vehicle records on used cars. According to Carfax, the records can potentially show everything from rebuilt wrecks to odometer fraud. Used-car buyers can run a preliminary Carfax record check for free, to see how many records are available on a specific car, or a used car they are thinking of buying. Just get the VIN number from the car, log on to www.carfax.com/record and follow the instructions.