On April 9, 1997, about 1942 central daylight time, a Cessna 182B, N2515G, registered to a private individual, collided with trees during a forced landing about 3 miles south of the Tullahoma Regional Airport/William Northern Field, Tullahoma, Tennessee. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 personal flight. The airplane was substantially damaged and the private-rated pilot was seriously injured. The passenger sustained minor injuries. The flight originated from the Cross City Airport, Cross City, Florida, about 3 hours 9 minutes earlier. The flight departed with full fuel tanks and while near the destination airport, the pilot noted that both fuel gauge indicator needles were fluctuating between 1/4 and empty. The flight continued toward the destination then during cruise flight at 3,000 feet about 5-6 minutes later and 3 hours 6 minutes into the flight, the engine quit. He initiated an emergency descent for a forced landing and with no suitable landing area, he elected to land the airplane in trees. During the tree contact, the left wing separated from the airframe. The airplane then descended through the trees and came to rest upright on the ground. The pilot stated postcrash that he has owned the airplane for about 20 years and the historical fuel consumption is 12.5 to 13.0 gallons per hour. Postcrash examination of the airplane by an FAA inspector revealed that the left wing fuel tank was found to contain about 1/4 cup of fuel and the right wing fuel tank was empty; both fuel caps were tightly secured and in place. No fuel stains were noted aft of each fuel cap or aft of each wing fuel tank sump drain fitting. The carburetor was examined and the inlet fitting was observed to be broken; no fuel was found inside the carburetor bowl. Fuel (100LL) was observed in the gascolator. According to a witness who was rendering patient care "One of the gentleman (the more slim one) stated they were trying to make it to Tullahoma Airport and they ran out of gas." Review of the FAA records for both occupants revealed that the pilot's weight based on an August 1995 medical was listed as 168 pounds, and the passengers weight based on a June 1995 medical was listed as 195 pounds. Straight line distance from the departure to destination airport was calculated to be 379 nautical miles. The first point of contact with the Jacksonville Air Route Traffic Control Center was at 1829.09 when the flight was located 118 nautical miles from the departure airport. The estimated time en route was calculated to be about 3 hours 13 minutes and based on the pilot report of historical fuel consumption of 13.0 gallons-per-hour, the estimated fuel consumption for the planned flight would be about 42 gallons. According to the Airplane Type Certificate Data Sheet, the usable fuel capacity is 55 gallons. No determination could be made as to the reason for the excess fuel consumption.