The objective was to identify if it was possible to change driver behaviour by economic incentives and thereby reducing crash risk. A one year Pay- As-You-Speed (PAYS) trial with economic incentives for keeping speed limits using Intelligent Speed Assistance (ISA) was therefore conducted in Sweden during 2011-2012. The full incentive was a 30% discount of the insurance premium. The participants were private insurance customers and they were randomized into a test group (initial n=152 and final n=128) and a control group (initial n=98 and final n=68). When driving the drivers in the test group were informed and warned visually when the speed limit was exceeded. They could also follow their driving results on a personal website. The control group was not given any feedback at all. For reflecting the impact of the PAYS concept the proportion of distance driven above the speed limit was compared between the two groups. The introduction of a PAYS concept shows that the test group significantly reduced the proportion of distance driven above the speed limit. The proportion of driving with a speed exceeding 5km/h over the speed limits was 6% for the test group and 14% for the control group. It also showed that the effect was higher the higher violation of speed. The result remained constant over time. A side effect of reducing speeding was that the fuel consumption was reduced and thereby the CO2 emissions. The results show that a PAYS concept is an effective way to reduce speed violations. Hence, it has the possibility to reduce crash severity and thereby to save lives. This could be an important step towards a safer road transport system. The majority of the participants were in favour of the concept which indicates the potential of a new insurance product in the future.