CART, which had sanctioned open-wheel racing in North America from 1979, declared bankruptcy after the 2003 season following the gradual departure of top teams and engine manufacturers to the rival IRL, which had been founded in 1996. Gerald Forsythe, Kevin Kalkhoven, and Paul Gentilozzi formed Open-Wheel Racing Series LLC to bid on CART's assets and continue the series independently. The IRL sought to undermine the bid by committing only to purchase CART's Cosworth engines and the sanctioning contract for the Grand Prix of Long Beach — moves intended to make the series financially untenable — but the OWRS bid prevailed, offering the highest probability that CART's vendors would be paid.
Champ Cars were single-seat, open-wheel racing cars with mid-mounted engines, sculpted undersides producing ground effect, and prominent wings for downforce. An alternative aerodynamic kit was used when racing on ovals. With development funds limited, the series ran primarily on CART-specification 2002 Lola chassis from 2003 to 2006 while work progressed on a new universal chassis. That chassis, developed by Panoz, debuted in 2007 as the Panoz DP01 and was well received by drivers and teams. The series leased 750 horsepower, 2.65-litre turbocharged Cosworth XFE V8 engines to teams; these had been purchased by CART for the 2003 season.
Once CART's assets were secured, the series scrambled to build a competitive field in time for the April 2004 Long Beach Grand Prix. The founding teams included Forsythe Championship Racing, Newman/Haas Racing, and Dale Coyne Racing. OWRS also acquired the Trans-Am Series and the Atlantic Championship. Champ Car maintained most of CART's street circuit sanctioning agreements and evolved into an effectively all road-course series, experimenting with rule changes including special compound tyres used for a fixed race portion, standing starts, and timed races.
Both Champ Car and the IRL continued to lose ground through reduced fields, declining sponsorship, and falling television ratings. Merger talks in 2006 collapsed after disagreements over Champ Car's forthcoming Panoz chassis and after leaked details of a potential shared series damaged relations with Indianapolis Motor Speedway. The 2007 season saw the withdrawal of Bridgestone and Ford as presenting sponsors alongside a reduction in the calendar.
By January 2008 both series feared they could not meet the minimum car-count thresholds required by their television and sanctioning contracts. After successful negotiations, Champ Car authorised bankruptcy proceedings in mid-February 2008 to facilitate a 22 February agreement in principle to merge with the IRL. The IRL purchased CCWS's sanctioning contracts, the Champ Car Mobile Medical Unit, the series history, and associated goodwill for $6 million. Forsythe and Kalkhoven each signed non-compete agreements in exchange for $2 million.
The first merged IndyCar Series event was the GAINSCO Auto Insurance Indy 300 at Homestead-Miami Speedway on 29 March 2008. However, a scheduling conflict with the Indy Japan 300 meant the 2008 Toyota Grand Prix of Long Beach — held on 20 April 2008 using CCWS-specification Panoz-Cosworth cars with IRL points awarded — was run as a Champ Car-sanctioned event and treated as a final celebration of the CART/CCWS era.
Spike TV broadcast all races in 2004, with select events also on HDNet in high definition. In 2005 and 2006 coverage was shared among NBC, CBS, and Speed Channel. In 2007 the series was carried across NBC, CBS, ABC, ESPN, ESPN2, and ESPN Classic.
Dale Coyne Racing, one of the original teams that continued racing after the merger, remains active in the IndyCar Series and is the only team from the Champ Car era to maintain that continuity.