The 2003 Pepsi 400, was a NASCAR Winston Cup Series race held on July 5, 2003, at Daytona International Speedway in Daytona Beach, Florida. Contested over 160 laps on the 2.5-mile (4.0 km) asphalt superspeedway, it was the seventeenth race of the 2003 NASCAR Winston Cup Series season. Greg Biffle of Roush Racing won the race, earning his first career Winston Cup Series win.