New research results from Carfax show that the number of cars with rolled-back odometers has increased 57 percent nationwide over the last four years. For that reason, used-car shoppers everywhere need to take every precaution to avoid becoming a victim of this rampant scam.

According to NHTSA, more than 450,000 cases of odometer rollbacks were reported in 2002, but that number is likely much higher today. Why? Experts believe digital odometers, used in the majority of vehicles built nowadays, are easier to manipulate. Plus, there's virtually no physical evidence of tampering.

Carfax offers car buyers these helpful tips to avoid buying a rolled-back car:

• Demand a Carfax Vehicle History Report from the seller;

• Examine the wear on the pedals, steering wheel, floor mats, etc. to make sure they are consistent with the mileage reading; and

• Have a trusted mechanic check the car's computer and inspect the vehicle thoroughly prior to purchase.

"Odometer fraud is alive and well," said Larry Gamache, communications director at Carfax. "Con men continually find ways to cheat the system, especially in a soft economy like this, and digital odometers are no exception. We cannot stress enough that consumers need to utilize every resource available to help protect them, starting with a Carfax Vehicle History Report. Simply asking the seller for a Carfax Report and questions about the car helps separate the good guys from the bad guys."

As a service to consumers, Carfax lets you check for potential odometer rollbacks free of charge at www.carfax.com/odo.

Buyer beware: A used car with low mileage may have had its odometer rolled back.