What is now the No. 4 car was Haas CNC Racing's original foray into NASCAR's top series, with driver Jack Sprague and sponsor NetZero. Haas' car became the No. 0 Pontiac. Sprague posted a career-best 14th-place finish at the 2003 Daytona 500 to open up the season. Afterwards, however, the team began to struggle. After finishing 40th at Chicagoland, Haas released Sprague in favor of John Andretti, who finished 41st at New Hampshire and 33rd at Pocono, before qualifying 15th and finishing 19th at Watkins Glen. Because Andretti had a prior commitment with Dale Earnhardt, Inc., Jason Leffler drove the car at the Brickyard 400, finishing 33rd. Leffler lost his ride with Ultra Motorsports, where he drove the No. 2 truck in the Craftsman Truck Series, because of his start at Indianapolis, but Haas hired him to drive the car on a more permanent basis shortly thereafter.