In October 2002 a first ISA-trial in Belgium was held in Ghent. Until January 2004, 34 cars and 3 buses were equipped with the “active accelerator pedal (AAP)”. This means when the driver attempted to exceed the speed limit, a resistance in the accelerator was activated. If necessary, the driver could overrule the system. To study the effect of the ISA-system both surveys and analyses of driving data were held. Data logging shows a clear effect of the ISA-system on speeding behaviour. Speeding reduces significantly. There is however still a large remaining percentage of distance speeding, especially in low speed zones. Differences between drivers are large. For some drivers speeding increases despite activation of the system. For less frequent speeders average driving speed almost always increases and for more frequent speeders average tends to decrease. Less frequent speeders tend to accelerate faster towards the speed limit and drive exactly at the speed limit in stead of safely below, which causes average speeds to go up.