Experts in California consumer law are warning car buyers about "yo-yo" scams, where people take the car home but then get called right back to the lot a few days later to sign new financing paperwork, often at a higher rate.

Many buyers don’t realize that the dealer can cancel the contract within 10 days. They’re supposed to give people their money back, but attorney Gregory Babbitt, a partner at the Auto Fraud Legal Center in San Diego, said some may be untruthful, telling clients that the financing fell through, or pressuring people if they resist a new offer.

"They tell them that they're not going to get their down payment back if they cancel the deal because they want them to sign a new contract," he said. "So those are the types of abuses that are going on every day, all the time."

New-car dealers who are on the up-and-up try to make the original finance contract work, because if they take it back, they have to resell it as a used vehicle.

Buyers can protect themselves by knowing their rights. They can also get pre-approved financing through a credit union, or use that pre-approval to negotiate a better rate at the dealership."

Oxnard attorney Sparky Abraham with Jubilee Legal said he has seen cases where the dealer missed the 10-day deadline, tried to take back the car anyway, and got nasty when the buyer tried to enforce the original deal.

"If the client tries to assert their rights under the contract, the dealer sometimes will just go nuclear and go straight to the police and report the car stolen, even though clearly it wasn’t," he said. "And the client can get arrested; I've seen clients lose their jobs, I've seen clients get prosecuted for stealing the car for many, many, many months before the charges are finally dropped."

Another variation on the scam involves a trade-in vehicle where the buyer owes more than it is worth. There have been cases where the dealer says they can’t return the person’s trade-in because it has already been sold, then says they won’t pay off the negative equity on the trade-in unless the buyer signs a new financial agreement.