The pilot reported that he planned the local flight in order to warm up the engine prior to an oil change. Upon returning to the airport, he entered a left downwind for runway 18 (2,575 feet by 30 feet, asphalt). On final approach he noticed that the airspeed was 75 knots instead of 70 knots, so he reduced engine power. However, the airplane did not slow sufficiently and he crossed the runway threshold faster than normal. The airplane ballooned during the flare and touched down short of midfield. He applied maximum braking, but was unable to stop on the remaining pavement. He directed the airplane between some trees at the end of the runway. After the airplane came to a stop he shut off the ignition and battery, and exited through the luggage door. The pilot reported that there were no failures or malfunctions associated with the airplane prior to the accident. He commented that he should have executed a go-around and returned for another landing at the proper approach speed.