R. J. Reynolds, manufacturer of Winston cigarettes and title sponsor of NASCAR's premier series since 1971, notified NASCAR leadership during the 2002 season that it intended to end its sponsorship prematurely at the close of 2003. NASCAR negotiated a replacement deal with Nextel Communications, a mobile telecommunications company, and the series was renamed beginning with the 2004 season. The Nextel name represented NASCAR's effort to realign its brand image with a corporate sponsor free of the advertising restrictions that had complicated the tobacco relationship.
In 2005, Sprint Corporation merged with Nextel Communications to form Sprint Nextel. This corporate change eventually resulted in a further renaming: beginning with the 2008 season, the series became the NASCAR Sprint Cup Series, ending the Nextel-branded identity after just four seasons.
The most consequential change introduced during the Nextel Cup era was a new playoff format for determining the series champion, known as the Chase for the Nextel Cup or simply "The Chase." Implemented in 2004 alongside the name change, it was influenced by formats used in other American sports series, specifically designed to keep the championship contest competitive later into the season and to improve television ratings during the NFL season.
Under the original Chase format, the ten highest-scoring drivers after the first 26 races of the season qualified for the championship playoff, which was contested across the final ten races. Their points were reset to a level mathematically unattainable by drivers outside the Chase field, ensuring only those ten could win the title. The first driver in points after 26 races started the Chase approximately 45 points ahead of the tenth-place driver. From 2007, the field was expanded from ten to twelve drivers.
The inaugural Chase in 2004 was won by Kurt Busch, who edged Jimmie Johnson by only eight points — exactly the kind of late-season drama the format was designed to produce. Johnson would go on to win the championship in 2006, beginning a period of dominance that would extend well beyond the Nextel era.
The Nextel Cup era coincided with the final years of the Generation 4 car, the body-style platform that had been in use since 1992. In 2007, NASCAR introduced a radically redesigned vehicle specification called the Car of Tomorrow, which made its debut at Bristol Motor Speedway that March. Initially fielded in only 16 events during 2007, the Car of Tomorrow featured a wider, taller body, a relocated driver's seat moved toward the car's center, redesigned bumpers, and a rear wing replacing the traditional spoiler. Full transition to the new car took place at the start of the 2008 season.
The fastest qualifying lap ever recorded on a NASCAR oval — 212.809 mph by Bill Elliott at Talladega Superspeedway in 1987 — remained the standing record throughout the Nextel Cup era, as restrictor plates introduced in 1988 prevented speeds approaching that mark.
Four champions claimed the Nextel Cup title across the series' four seasons. Kurt Busch won the inaugural Nextel Cup in 2004. Tony Stewart won in 2005. Jimmie Johnson claimed the title in 2006, and Jeff Gordon took his fourth championship in 2007. The 2006 and 2007 titles won by Johnson and Gordon reflected the continued dominance of Hendrick Motorsports during this period.
The series raced under the Nextel Cup name for the last time at the 2007 Ford 400 at Homestead-Miami Speedway. Although the Nextel-Sprint corporate merger had occurred in 2005, NASCAR honored the existing sponsorship contract through 2007 before rebranding to Sprint Cup for the 2008 season. The Chase playoff format introduced during the Nextel Cup years remained the championship structure going forward and continued to evolve through successive rule changes in subsequent seasons.