On March 18, 2003, at approximately 0920 mountain standard time, a Panzl PAN homebuilt experimental airplane, N11ZL, was substantially damaged during impact with terrain following a forced landing attempt near Vernal, Utah. The commercial pilot, the sole occupant on board, received minor injuries. The flight was being conducted under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the cross-country flight that originated at approximately 0800 from Steamboat Springs, Colorado. The pilot had not filed a flight plan. The pilot told local police officials that he had just purchased the airplane, and was flying it to his home in Reno, Nevada. The previous owner said that the pilot told him that he had flown airplanes similar to this airplane, but this was his first flight in the PAN. The pilot said that as he approached the Vernal Airport, the engine lost power due to fuel exhaustion, and he performed a forced landing on Highway 40. He said he had to maneuver the airplane to miss some transmission wires, and he encountered a quartering tail wind (020 degrees at 15 knots, gusting to 22 knots) that was blowing across the highway. The highway was elevated 10 to 14 feet above the surrounding terrain. The pilot said that the airspeed indicator was indicating 100 miles per hour, but the airplane contacted the highway at a high rate of descent. During the subsequent hard landing, the landing gear was "pushed" into the wings. Postaccident examination of the airplane revealed that the lower right wing spar was broken, and the top right wing had wrinkled skin. The engine's firewall was also bent and rippled. The previous owner said that the main fuel tank (header/fuselage tank) held 18 gallons of fuel, and the auxiliary (wing) tank held 9 gallons. He "stuck" [measured fuel tank levels with a stick] the fuel tanks just before the pilot's departure, and estimated that there were 15 to 16 gallons of fuel in the main tank and the wing tank was full. The airplane's engine burned approximately 12.5 gallons per hour. The previous owner said that he "never" used the auxiliary position on the fuel selector. He said that he would burn from the main fuel tank for approximately 1 hour, then he would select the "both" position. When the "both" position was selected, the wing tank fuel would drain into the main fuel tank, but the engine fuel supply would continue coming directly from the main fuel tank. If the auxiliary position was selected on the fuel selector, the fuel would flow from the wing tank directly to the engine. The pilot said that he estimated the flight time to Vernal [his first fuel stop] to be approximately 1 hour. He said that during his preflight aircraft check, he did not personally check the fuel tanks because he wanted to get airborne (some weather was coming in). The pilot said he "burned" from the main fuel tank for approximately 1 hour, and then moved the fuel selector to the auxiliary position (his written statement states that he turned to the "both" position). Approximately 20 minutes later, the engine began to lose power. The pilot said that he switched the fuel selector back to the main position, but because of his low altitude, he could not get the fuel injected engine restarted in time. After the landing, the auxiliary wing fuel tank was found to be empty, and the main fuel tank had 3 to 4 gallons in it.