From beat up old cars to gas guzzling SUV's, dozens of trade-in vehicles have been brought in to Elk Grove Nissan under the new "cash for clunkers" program.

"From a 1995 Chevy Blazer to a 1991 Caprice, they've all qualified for the program," said Amy Rothenberger of Elk Grove Nissan.

People who trade-in a car for a more fuel-efficient vehicle can receive between $3,500 and $4,500 toward a new one.

"These are vehicles that are high mileage, 175 thousand miles in some cases, that before this program would be worth maybe $500 as a trade in value," said Rothenberger.

But the devil's in the details. The trade-in must get 18 miles per gallon or less and be a 1984 model or newer. Your clunker must be driveable, and don't think about flipping an old car for profit, it must be registered in your name for at least a year. Even if your car meets those restrictions, you still may not want to participate in "cash for clunkers." It may be better just to trade-in a car that's worth, for example, $10,000. The program doesn't give you the $4,500 on top of the trade-in value.

"My car is worth more. It's not worth trading in," said Jim Brown.

"I wouldn't benefit much from that, unless perhaps you're looking at long term," said Lance Lee.

Restrictions also appy for the new car. It must be brand new and get at least 22 miles per gallon or better. The car also can't be more than $45,000.

The nationwide program officially launches on Monday, but Elk Grove Nissan has been accepting trade-ins since July first.

"We took a little bit of a gamble, but the rules were very clear. We were very careful to make sure the miles per gallon matched, that the registrations were current," said Rothenberger.