Three of the four manufacturers already had unveiled their cars—the Ford Fusion, Dodge Charger and Toyota Camry—with the caveat that they could be altered pending final approval.
Chevrolet has not unveiled its new SS.
NASCAR has had all the cars in the wind tunnel several times in order to achieve parity among the manufacturers.
“With all the designs and surface areas of the car now approved, manufacturers can now move forward with building the components needed to outfit their cars," NASCAR vice president of competition Robin Pemberton said in a statement.
“The wind tunnel testing we’ve had with the manufacturers over the past several months has given us the timely and necessary data we needed to come to this confirmation. We believe the new car is going to be a milestone opportunity for our sport, one that our fans will embrace."
NASCAR tentatively plans to open Talladega Superspeedway for a test of the new cars the Wednesday and Thursday prior to the Oct. 7 race weekend there. Additional tests at NASCAR tracks are expected.
“The fans have clamored for the return of cars that look like cars in their driveways, and NASCAR, alongside us as manufacturers, (has) listened to that request," said Ford Racing director Jamie Allison.
While it has submitted a car for 2013, Dodge has not announced whether any teams will compete with manufacturer backing next year. The lone Dodge team, Penske Racing, is moving to Ford for 2013.