The pilot planned on a long cross-country flight. According to the pilot, he made a fuel stop and got something to eat and drink, and then continued the flight. As he approached his next stop, he reported that he contacted the tower controller, who cleared him for a right base for the runway. The airplane approached the runway, flew about 1,000 feet down the runway, and then drifted off to the right. The airplane then flew across a parallel taxiway, made a right turn, and impacted terrain, just east of the runway. The pilot reported that he did not remember the accident, nor climbing out of the airplane. By the time the first responders arrived, he was able to walk around the airplane and waved to them to indicate that he was not injured. He added that the last thing he remembered, was making the approach, and then looking at the wrecked airplane. Examination of the airplane revealed substantial damage to the fuselage. The airplane was not equipped with carbon monoxide detectors, however, the heat exchanger had been removed and the ports plugged, and no indications that carbon monoxide had leaked into the cabin. The examination did not reveal any mechanical anomalies that would have precluded normal operation. Additionally, the pilot reported no problems with the airplane prior to the accident. The pilot added that he was given several tests at the hospital, but doctors told him it was probably due to dehydration.