The NASCAR Sprint Cup Series is the sport's highest level of professional competition, and consequently it is the most popular and most profitable NASCAR series. The 2006 season consisted of 36 races over 10 months, with over $4 million in total prize money at stake at each race. Writers and fans often use "Cup" to refer to the Sprint Cup series, and although ambiguous, the use of "NASCAR" as a synonym for the Sprint Cup series is common.

NEXTEL took over sponsorship of the premier series from R.J. Reynolds in 2004, formally renaming it from the Winston Cup to the NEXTEL Cup Series. (NEXTEL's merger with Sprint resulted in the cup series being renamed, beginning with the 2008 season.) A new championship points system, The Chase for the Sprint Cup was also developed, which re-set the point standings with 10 races to go, making only drivers within the top 10, or within 400 points of the leader, eligible to win the championship.

In 2004, Kurt Busch became the first driver to win the Sprint Cup under the new format. In 2005, Tony Stewart became the first driver to win both the Winston Cup and the Sprint Cup. In 2006, Jimmie Johnson won his first Sprint Cup, after coming close twice before, by finishing 9th at Homestead-Miami Speedway. He won his second championship in 2007.

In 2007, NASCAR announced they were expanding "The Chase", as it is sometimes called, from 10 to 12 drivers, eliminating the 400-point cutoff, and giving a 10 point bonus to the top 12 drivers for each of the races they have won out of the first 26.