Thousands of motorists in New Jersey could be unknowingly driving a vehicle that has been severely flooded or in a serious wreck. According to Carfax, New Jersey is number one for a scam known as "title washing."

Vehicles damaged by Sandy at Insurance Auto Auctions in Morganville, NJ (Townsquare Media)

Think of it as a high-tech version of changing a grade on a report card. Professional con men are successfully removing any indication of flood damage or accidents from cars' titles. With a clear history, the car can be easily resold, but with some potentially dangerous problems lurking.

"They alter title documents, and they move these rebuilt, wrecked cars from state to state so they're able to produce a clear title to a potential buyer," said Chris Basso, public relations manager for Carfax.

The company's data suggest there are nearly 80,000 cars with a washed title on New Jersey's roads. Basso said the scam's uptick in the Garden State can be attributed to damage from Superstorm Sandy and the fact that buyers here are not doing enough to research a car's history before purchase.

"The overwhelming majority of these cars are going to be sold on the side of the road by private individuals, or through online sites like Craigslist," Basso said. "One of the key steps towards avoiding this issue is shopping at a reputable dealer."

He said potential buyers, before laying down their hard-earned money, should also put the vehicle they want through an in-depth inspection by a trusted mechanic.

A spokesperson for the state Motor Vehicle Commission cited an uptick in title washing issues since Sandy made landfall.

In February 2013, the state launched an online database to prevent vehicle fraud. Consumers can search the database by Vehicle Identification Number, make, model and year to verify whether an automobile has been damaged by flood or other means.