From the official web site for the program:
How do I know if a dealer is participating in the program?
The law requires dealers to be registered to participate in the program. We will be moving as quickly as possible to register interested dealers as soon as the registration process begins in the near future. As dealers are registered, we will list them on this website. We will continue to update this list during the life of the program. Meanwhile, you may wish to contact dealers in your area to ask whether they plan to participate in the program. The CARS Act requires that dealers be licensed by their respective state for the sale of new automobiles in order for them to participate in the program.
Is there a cap on the price of the vehicle I can buy or lease under the program?
Yes. The manufacturer's suggested retail price cannot exceed $45,000.
Does the program apply if I want to buy a used car?
No. The program does not apply to the purchase of used vehicles.
What is the amount of the credit?
The amount of the credit is $3,500 or $4,500, and generally depends on the type of vehicle you purchase and the difference in fuel economy between the purchased vehicle and the trade-in vehicle. Different requirements apply for work trucks.
In addition to the credit, will I get the full value of my trade-in vehicle?
No. 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. The law requires the dealer to disclose to you an estimate of the scrap value of your trade-in vehicle.
I don't drive an American car but I would like to trade in my old car for a newer, more fuel efficient one. Is this program only for American cars?
No. You may trade in or buy a domestic or a foreign vehicle.
I just traded in my old car for a new vehicle last month. Will I get some money back?
No. The program does not apply retroactively.
Is the credit subject to being taxed as income to the consumers or dealers that participate in the program?
The CARS Act expressly provides that the credit is not income for the consumer. However, the credit will be considered as income for the dealer.
Can I use the credit in combination with manufacturer rebates or discounts?
The CARS Act requires the dealer to use the credit under the CARS program in addition to any rebates or discounts advertised by the dealer or offered by the new vehicle's manufacturer. The dealer may not use the credit to offset these rebates and discounts.