The car was introduced in the 2007 Cup season at the Food City 500 on March 25 and ran a partial schedule of 16 races. The plan was to require all teams to use the new car in 2009, but NASCAR officials moved the date up to the 2008 season.

On January 11, 2006, NASCAR announced the Car of Tomorrow after a seven-year design program sparked mainly by the death of Dale Earnhardt Sr. in a final-lap crash during the 2001 Daytona 500. The then-current cars were based on a design by Holman Moody first used for the 1966 Ford Fairlane. The primary design considerations were "safety innovations, performance and competition, and cost efficiency for teams."

The CoT has improved safety over the older car. The driver's seat has been moved four inches to the right, the roll cage has been shifted three inches to the rear, and the car is two inches taller and four inches wider. Larger crumple zones are built into the car on both sides. The splitter is a piece of fiber-reinforced plastic (FRP, "fiberglass") used on the bottom front of the car to produce downforce, replacing the valence. The car's exhaust exits on the right side, which diverts heat from the driver. The fuel cell is stronger, and has a smaller capacity 17.75 US gallons (67.2 L), down from 22 US gallons (83 L), which as of 2007 has become standard in all cars].

NASCAR officials say the car is less dependent on aerodynamics. It has a detached wing, which has not been used since the Dodge Charger Daytona and Plymouth Superbird in 1970. The windshield is more upright, which increases drag. The radiator air intake is below the front bumper of the car, which reduces overheating caused by clogged grilles. The front bumper is more box-like, which catches more air and slows the car. The front airdam is gapped, as opposed to being a flush piece on the older cars.

All cars are required to fit the same set of templates, using a device that has been named "the claw" that is designed to fit over the new cars. Yet there are still minor differences between the makes. In the first two races at Bristol and Martinsville Speedway, the garages were opened one day early and the inspections took up to 10 hours so that everyone (teams, officials, etc.) could get a better grip on the new unified template. NASCAR's old rules had a different set of templates for each manufacturer (Ford, Chevy, Dodge, and Toyota). NASCAR has frequently adjusted the rules to ensure that different car manufacturers have relatively equal cars.

On Friday, January 15, 2010 Sprint Cup Series director John Darby informed teams NASCAR will transition back to the spoiler, and get rid of the rear wing because it is contributing to flips. (NASCAR has never stated the wing contributed to flips, the return to the spoiler is purely aesthetic and to apease fans; however, three cars flipped from November 2009 until March 2010 from violent crashes with the 16-degree wing – Ryan Newman and Mark Martin at Talladega in November 2009, and Brad Keselowski's flip in March 2010.)[citation needed] The size and shape of the new spoiler is still to be determined and earliest implication will come at the spring Martinsville race on March 28. Cars will lose advertising space, as the wing plates were used by sponsors for additional advertising space on the cars, and there is no equivalent advertising space on spoilers. The wing plates also affected handling.

This chart lists the CoT's dimensions compared with the dimensions of the cars represented.

*Weight displays the curb weight of the least expensive trim level available for model year 2008 unless otherwise specified.

The Car of Tomorrow was first tested in December 2005 at Atlanta Motor Speedway. Next it tested at the 2.5 mile Daytona International Speedway, then on NASCAR's two shortest tracks, Bristol (0.533 mi) and Martinsville (0.526 mi.), the 1.5 mile Lowe's Motor Speedway, the 2.66 mile Talladega Superspeedway, and 2.0 mile Michigan International Speedway. Former NASCAR driver, current Sprint Cup pace car driver and Director of Cost Research Brett Bodine also tested the prototype car against cars prepared by current NASCAR teams.

Drivers have tested the CoT concurrently with the old car at some NASCAR tests and at special NASCAR-authorized tests. Some teams have tested the cars at the half-mile Greenville-Pickens Speedway, Caraway Speedway in Asheboro, NC, and the one-mile North Carolina Speedway, none of which are Sprint Cup tracks (the North Carolina Speedway was a regular venue until 2005), and therefore are tests which do not fall under NASCAR's restrictions.