Most consumers do not know the biggest warning signs indicating a vehicle may have been in a major accident, according to a poll conducted by CarMax, Inc.

More than 70 percent of respondents said that repainting the car is the strongest indicator of vehicle damage. According to CarMax's knowledgeable car-buying professionals, however, clamp marks on a vehicle's frame are the biggest sign that the car may have been involved in a serious collision.

"A car might be repainted to address cosmetic issues rather than a serious accident," said David Claeys, purchasing manager for CarMax in Richmond, Virginia. "Paint work isn't as big of an indicator as clamp marks on the frame of the vehicle. People should be sure to do their research and look beyond a paint job when buying a used car and consider several other factors in order to spot hidden signs of prior vehicle damage."

The following are the results of a carmax.com "Quick Poll" where 4,837 carmax.com visitors were asked to identify the strongest indicator that a car has suffered serious vehicle damage.

"Used car shoppers need to be on the look out for signs a car may have been in a bad accident, as the safety and resale value of the car may have been compromised," said Claeys. "Cars that have had severe structural damage can be completely repaired, retitled, and sold to an unsuspecting buyer. Minor fender benders often do not compromise the integrity of the vehicle and are not as much of a concern."

CarMax's car buying team recommends the following tips to help determine whether a used car may have been in a serious accident.

• Look for clamp marks on the frame rail under the car. Clamp marks look like holes or gashes on the frame of the vehicle. Clamp marks usually indicate that the car has been on a frame machine, which suggests the vehicle may have been in a serious accident.

• Check the bolts used to fasten fenders, doors and the trunk lid to see whether the paint is broken or bolts are turned, which could indicate the bolts were removed for body repairs to the vehicle.

• Peel back the fabric that lines the trunk and look for welding marks or body filler, which may indicate that repairs were made on the body of the vehicle.

• Look for signs of repainting on the car, such as inconsistency in the paintwork or paint on the molding or gaskets. Run your finger along the inside of the door edge and see if the finish is smooth or rough. A rough finish can be caused by overspray during repainting. If signs of repainting are found, ask additional questions to determine if the paintwork was for minor scratches and dents or to cover up more serious vehicle damage.

• Listen for any engine noise when you test drive the vehicle. A major accident can cause damage to any part of the engine. Ask questions about any noise that sounds unusual.

• Check to see if all the doors, the hood, and trunk lid close properly. If they don't, this could indicate the use of replacement parts due to a major accident.

• Check to see if the odometer changes miles as the vehicle is driven.

• Check the vehicle identification number, or VIN, on the dashboard and see if it matches the VIN on the sticker inside the door of the vehicle. If the numbers do not match, the door may have been replaced.

• Review reports from AutoCheck or Carfax with the VIN to determine if there are any reports of the vehicle as stolen, declared a lemon, or previously involved in a serious collision.

CarMax's nationwide team of approximately 1,000 car-buying professionals has appraised more than 9 million cars. These buyers are trained to detect possible signs of vehicle damage and whether a car has been in a major accident. CarMax will not retail any used car that has frame or flood damage or an inaccurate mileage count on the odometer.

CarMax will buy any car, whether or not the seller purchases a CarMax vehicle. Cars not meeting CarMax's stringent mechanical, electrical and safety standards are sold to dealers at in-store wholesale auctions. More than half of the cars the company retails are purchased directly from consumers.