The 2005 GFS Marketplace 400 was a NASCAR NEXTEL Cup race held August 21, 2005, at Michigan International Speedway. Jeremy Mayfield won the race on a fuel-mileage gamble in the closing laps of the race, taking the lead from unsponsored driver Tony Raines, who had also attempted to stretch his fuel tank. This would be Mayfield's final win with Evernham Motorsports. In the points race, Tony Stewart expanded his points lead over Jimmie Johnson to 126 points.