The pilot stated that he performed a preflight inspection and engine run and noted no defects with the airplane’s brakes or flight instruments. When the airplane was about halfway down the runway during the takeoff roll, the pilot saw that the airspeed indicator was not functioning and decided to abort the takeoff. The pilot moved the throttle to idle and applied the brakes, but the airplane did not slow as expected, and the airplane continued to roll to the end of the runway. Despite maximum braking efforts, the airplane overran the end of the runway and impacted a drainage culvert. The pilot and passengers exited the airplane before it was destroyed by a postcrash fire that originated from the engine area. Though the pilot reported malfunctions of the airspeed indicator and brakes, the postcrash fire destroyed most of the airplane, and precluded an examination of these systems. As a result, the reasons for the reported failure of the airspeed indicator and brakes could not be determined based on the available evidence.