First of all, it’s no longer Cash-for-Clunkers. The program is now called the Car Allowance Rebate System (C.A.R.S.).

The program, which President Obama signed into law on Thursday, pays consumers up to $4,500 in credit for trading in their cars or trucks for those that are more fuel efficient. The law allocates $1 billion for the program.

Of course, there are plenty of regulations to determine what vehicles qualify for the credit. The National Highway Traffic Safety Administration, which is overseeing the program, has put together this Web site to help consumers who would like to participate in the program.

In a nutshell, your vehicle qualifies for trade-in credit if:

• It is at most 25 years old.

• It gets 18 miles a gallon or less.

• It is drivable.

• It is registered.

• It has been insured for the past year.

You can find out what gas mileage your car or truck should get here.

The C.A.R.S. rebate does not count on top of the trade-in value of your vehicle. In the F.A.Q. section of CARS.gov: “The law requires your trade-in vehicle to be destroyed. Therefore, the value you negotiate with the dealer for your trade-in vehicle is not likely to exceed its scrap value.”

N.H.T.S.A. has 30 days to roll out the details of the plan, which ends Nov. 1 (or when the money runs out). Until more details are released, here are some links that might be worth reading:

• N.H.T.S.A. warns consumers of unofficial C.A.R.S. Web sites that are now popping up, reports USA Today. “Some want a lot of personal information, and talk about consumers being able to pre-register,” said Eric Bolton, a N.H.T.S.A. spokesman. “Consumers don’t have to register for this program at all.”

• Businessweek quotes the chief executive of Edmunds, Jeremy Anwyl, who said C.A.R.S. won’t help the auto industry climb out of its current situation. “The scale is all wrong,” he said, adding that auto sales need to increase by three million vehicles or more, not 250,000 to 400,000.

• The Washington Post calls the program a “bad idea.” In a recent editorial, The Post also noted that the expected result (moving some 250,000 cars) is too limited. “Those paltry results will merely represent the shifting of future demand for cars to the present; they will also come at the expense of sales of other goods that people might have chosen to buy this summer or fall,” The Post said.

So, does C.A.R.S. have any backers? So far, it’s mainly just the automakers — Ford has its own C.A.R.S. site — and auto dealers, though not used car dealers.