A PA28 pilot failed to slow his final approach speed then did not execute a go around after realizing that his approach was unstabilized; landed long and so overran the runway end.

Narrative

I overran Runway 32. I was cleared for a visual to Runway 32. I was at 2;000 FT MSL and on a 45 degree intercept. It was the ideal time to test the operation of my GPS/autopilot operation to the artificial 'ILS' that the GPS generates. I set up the radios and autopilot and it performed flawlessly. Usually; when arriving at this airport; I am requested to 'keep up my speed' and asked to fly my approaches as fast as possible. I guess that must have been in the back of my mind as I did not throttle back as much as I normally would. While on the descent; I felt uncomfortable with my speed/position at about 1;000 FT MSL. I then decoupled the autopilot and slipped the plane down and began to attempt to slow down. When I was about 100 FT AGL; I was still a little above flap extension speed. I got there near the runway threshold and elected to land. I continued down the runway; bleeding off speed and then landed. On rollout; I realized that I would have trouble stopping prior to the end of the pavement. I applied significant braking; but when I realized that I would still be moving at the end; I stopped braking and raised the nose to assure no damage. I then rolled onto the grass at the end of the runway about 50 to 75 FT. I taxied back to the runway and was instructed by the Tower to stay where I was. A number of emergency vehicles were dispatched and upon arrival realized that there was no damage to my aircraft. I then contacted Ground Control and taxied to the ramp. In retrospect; I should have declared a missed [approach] when I decoupled the autopilot and; if not then; when I was just near flap extension speed at the end of the relatively short runway.