The pilot reported that after 2 hours and 15 minutes of cross country flight, the left engine lost power and began to surge. The pilot contacted Air Traffic Control, declared an emergency, and asked for vectors to the nearest airport. During the descent toward an abandoned airport, the left engine continued to surge and the pilot went to full rich on both engines, turned on the fuel boost pumps, checked the magnetos, and checked the fuel valves. As the airplane descended through 3,000 feet, the right engine surged and lost power. The pilot assessed that he could not make it to the airport and selected a farm road to try to land. While turning from base leg to final approach for the road, the pilot lowered the landing gear and assessed that he not be able to make the road. Subsequently, the airplane hit the tops of trees about 50 feet from the road and descended to the ground with the main landing gear touching down first. As the nose landing gear touched the ground, the airplane flipped over inverted, resulting in substantial damage to the front of the fuselage and the rudder. Emergency responders to the accident scene reported that they did not see or smell the presence of fuel around the wreckage. An FAA inspector who responded to the accident site did not find evidence of fuel in the wreckage or the surrounding area. After the accident, the pilot initially stated to an FAA inspector that he ran out of fuel and he was not certain of the amount of fuel that was in the airplane when he initially departed on the flight. In a written statement, the pilot reported that he estimated he had about 136 gallons of fuel on board prior to commencing the flight. He noted that the amount was an estimate from a visual inspection during preflight.