The flight instructor reported that, during the preflight inspection, he asked the student pilot, who was the owner of the airplane, how much fuel was onboard the airplane and that the student replied that there was enough fuel for about 3 hours of flight. He added that, during the flight, he became concerned about the fuel level because he saw that the right fuel gauge needle displayed "little movement." After a brief conversation with the student about the fuel burn, the instructor decided to return to the airport. The student stated that he visually checked the fuel tanks during the preflight and estimated that there was about 1/2 tank (19 gallons), which was enough for about 2.5 hours of flight based on a fuel burn of 7.5 gph. The student reported that, during the flight, the instructor commented that the fuel gauge looked low and that he responded that it was working "intermittently," at which point, the instructor decided to return to the airport. The student reported that, about 5 nautical miles from the airport, the airplane "ran out of fuel at 3,000 ft MSL [mean sea level]." Subsequently, the instructor landed the airplane on a road, and the right wing struck a power line pole. The airplane sustained substantial damage to the right wing.