Because the performance charts indicated that the strip length available could be marginal, for the takeoff, the pilot carried out a physical check using the odometer of a car. This confirmed a usable length of seven hundred metres. The pilot reported that during the takeoff roll the aircraft was accelerating normally until approximately mid way down the strip, at which point the acceleration rate of appeared to slow considerably. He then elected to abandon the takeoff, as the speed was still below that required to safely become airborne. He applied brakes and full flap, but was unable to prevent the aircraft overrunning the end of the airstrip and colliding with a wire fence.