The pilot reported that, 15 minutes into a cross-country flight, the airplane's engine lost rpm. He added power and the engine regained rpm briefly, before losing all power. The pilot selected a dirt road for an emergency landing. Subsequently, during landing on a dirt road, the nose landing gear touched down on a soft surface, and the airplane nosed over. The pilot reported on the NTSB form 6120.1 that the airplane had 4.5 gallons of fuel on board at the last takeoff. The airplane sustained substantial damage to the left and right wings, and the front windshield. A Federal Aviation Administration inspector reported that, during the postaccident examination of the airplane, the fuel tanks were found empty. The gascolator had residual fuel, and about 1 gallon of fuel was removed from the fuselage fuel drain. He added that according to the manufacturer's specifications the accident airplane should have 1.5 gallons of unusable fuel. He turned on the airplane's master power switch to view the fuel quantity gauge indications, and the left-wing tank gauge indicated between empty and a quarter full with no fuel in the tank, and the right-wing fuel tank gauge indicated empty.