On July 24, 1999, about 0900 hours Pacific daylight time, a Cessna 172E, N5784T, sustained substantial damage when it lost engine power and made a forced landing on Interstate 80 in Emeryville, California. Aerodrome of Redlands, California, operated the rental airplane under the provisions of 14 CFR Part 91. The private pilot and one passenger were not injured. The airplane departed Redlands about 0520 en route to Hayward, California, on a personal flight. Visual meteorological conditions prevailed and a VFR flight plan had been filed. The pilot stated his destination was overcast with thick clouds so he flew inland to get under them. He was level at 1,500 feet under the overcast about 10 miles north of Hayward, when the power went to zero. The engine started, and then quit two more times. His altitude was about 500 to 600 feet agl, so he set up to land on the interstate highway. The pilot thought he might hit a car, so he pulled the nose up into a full stall. He hit hard, the nose gear collapsed, and he hit a road sign with his right wing. The airplane spun 90 degrees to the right and nosed into a chain link fence. No vehicles on the ground were damaged. Two motorists who observed the accident were pilots. One of them swerved across the lanes of traffic to make a traffic break so that the pilot would have a clear landing path. The airplane's flight manual listed a total capacity of 42 gallons of fuel with 39 gallons of useable fuel. The airplane had an auxiliary fuel tank installed, but the pilot felt he had enough fuel onboard to make the flight without filling it. The airplane had been modified so that the original 145 horsepower Continental engine had been replaced with a 180 horsepower Textron Lycoming engine with a constant speed propeller. The Federal Aviation Administration (FAA) accident coordinator looked onboard the airplane, but did not find any supplements or changes to the airplane flight manual regarding this modification. The pilot's flight planning estimated the flight would take 3 hours 3 minutes, and that he had 4 hours of fuel onboard. The pilot planned a fuel burn of 9.7 gallons per hour. His actual flight time was about 3 hours 40 minutes. The airplane flight log indicated the tachometer reading at the time of departure was 276.0. The FAA accident coordinator noted a reading of 280.5 after the accident. The pilot noted during his preflight inspection that the right tank was full and the left tank was down about half an inch. He noted in his written statement that the left gauge indicated between the 1/4 and 1/2 levels at the time of the accident. The FAA accident coordinator inspected the airplane at Plain Parts in Sacramento, California, on July 29, 1999. The recovery agent told the coordinator that he drained the fuel system prior to removing the wings during recovery. He recovered no fuel from the right wing, 2 drops of fuel from the left wing, and less than 3 ounces from the fuel sump. The recovery agent placed a can of fuel on top of the wing and plumbed it to the engine. He started the engine after about five revolutions and allowed the engine to idle. He ran the engine up and completed a functional check of the magnetos and propeller. He ran the engine at full power, and then completed a normal shutdown. The coordinator detected no discrepancies during any of the functional checks.