The CoT project formally began in the wake of four NASCAR driver fatalities in an eight-month span from May 2000 to October 2000: Adam Petty, Kenny Irwin Jr., Tony Roper, and ultimately Dale Earnhardt himself in February 2001. The then-current cars were based on a Holman Moody design first used for the 1966 Ford Fairlane. NASCAR launched its development program with three primary goals: safety innovation, performance and competition equity, and cost efficiency for teams.
On January 11, 2006, NASCAR publicly revealed the Car of Tomorrow following the five-year program. The design was larger and boxier than its predecessor, two inches taller and four inches wider. Critics immediately noted its generic, homogeneous appearance, but NASCAR focused attention on the safety improvements embedded throughout the new platform.
The Car of Tomorrow incorporated several structural changes compared to the Generation 4 car it replaced. The driver's seat was moved four inches toward the center of the chassis, and the roll cage shifted three inches rearward. Larger crumple zones and impact-absorbing foam were built into both sides of the car. The fuel cell was reinforced with thicker material and reduced in capacity from 22 gallons to 17.75 gallons.
An adjustable splitter made of fiber-reinforced plastic replaced the front valance, producing downforce while keeping the front profile lower. The exhaust system was routed to the right (passenger) side to divert heat away from the driver. The windshield was made more upright to resist collapse in rollovers, and the radiator air intake was relocated below the front bumper to prevent debris-clogged overheating.
The car initially featured a rear wing rather than a traditional spoiler — the first use of a wing in NASCAR competition since the Dodge Charger Daytona and Plymouth Superbird of 1970. The wing was later replaced by a conventional spoiler in 2010 after several high-profile airborne accidents were attributed to its aerodynamic properties at superspeedways.
A unified template system called the laser inspection device, nicknamed "the claw," was introduced to enforce the new shared chassis rules across all manufacturers. Unlike the old rules, which allowed different templates for Ford, Chevrolet, Dodge, and Toyota, the CoT required all cars to conform to the same set of dimensions with only minor cosmetic differences.
The Car of Tomorrow made its race debut on March 25, 2007, at the Food City 500 at Bristol Motor Speedway — the fifth race of the season. Kyle Busch won that inaugural event, claiming the first Cup Series victory for the Chevrolet Impala since Wendell Scott's historic 1963 win. Reactions to the debut were mixed. Dale Earnhardt Jr. noted it "wasn't a disaster like everybody anticipated," while Busch himself, despite winning, said in victory lane that the cars "suck."
The CoT ran 16 races during the 2007 season as a partial-schedule introduction. NASCAR originally planned to mandate the car for all races by 2009, but moved the deadline up to the 2008 season as a cost-saving measure, requiring all teams to convert one year earlier than planned.
Over the 2007–2012 period, 28 different drivers scored Cup Series victories in 196 CoT races, including several first-time winners. The era was statistically competitive, with the first four CoT races in 2007 producing more quality passes for top-15 cars than their 2006 counterparts. However, criticism of the car's handling in traffic — particularly the aerodynamic push it created when following another car closely — persisted throughout its lifespan.
The rear wing proved especially problematic at superspeedways. In the 2009 Aaron's 499 at Talladega, Carl Edwards was turned into the air on the final lap and his car bounced off Ryan Newman's hood before flipping into the catch fence, injuring seven spectators. Similar airborne incidents at Atlanta in 2010 added to calls for the wing's removal. By February 2010, NASCAR confirmed it would replace the wing with a rear spoiler beginning at the Goody's Fast Pain Relief 500 that spring.
The 2008 Brickyard 400 at Indianapolis Motor Speedway exposed another weakness: extreme tire wear caused by the CoT's lack of downforce and higher center of gravity on the track's rough surface. Most cars could run no more than 10 laps before requiring a pit stop for fresh tires, making for an interrupted and widely criticized event.
For 2011, the car's nose and splitter were redesigned. The splitter braces were removed, the splitter itself was made non-adjustable, and the nose received a rounder, cleaner look that gave manufacturers more freedom to reflect their production-car identities in the lower grille area. The 2011 Daytona 500 broke records for leaders and lead changes — 22 drivers changed the lead 74 times — partly due to a new two-car tandem drafting phenomenon that emerged on resurfaced Daytona pavement.
Following the elimination of the CoT in 2013, NASCAR Chairman and CEO Brian France publicly identified the Car of Tomorrow as his biggest failure as head of the sport, citing the lack of manufacturer identity it produced. Its replacement — the Generation 6 car — allowed manufacturers to design new body styles that more closely resembled their production counterparts, while retaining the CoT's chassis safety improvements and adding a carbon fiber hood and decklid that reduced weight by 160 pounds.
No NASCAR Cup Series driver fatalities occurred in competition from the introduction of the Car of Tomorrow through the end of its era, a record the car's designers pointed to as proof of the program's core success. The CoT chassis remained in service through the end of the 2021 season before the Next Gen car debuted in 2022.
The Xfinity Series (then the Nationwide Series) adopted its own CoT variant beginning with a partial schedule in 2010, using the same chassis but with an extended wheelbase and different body styles oriented toward American pony cars such as the Ford Mustang. The series moved to the CoT full-time in 2011.