In 1987 TNO Automotive started the execution of a large scale in-use compliance program for passenger cars. The initial goal of the program was: 'Monitoring the emission performance of passenger cars in-use and relating this performance to the situation at type approval'. In the early years the program proved to be very useful for detection of emission reduction technology not performing up to the type approval specifications, while in use. With increasing performance and reliability of passenger car technology, the number of failing cars decreased significantly, only diesel cars still show some problems. Over the years, the program has proved to be a very important data source for determining emissions of the Dutch national car fleet. The Dutch national emission modeling is based on data from the in-use compliance program. Especially emission data gathered on real world test cycles prove to be of increasing importance. Because of changes in the European emission regulations (Euro III), new fields of in-use compliance testing have to be addressed. The main new topics are: Ultra low emissions, EOBD and cold start at -7° C.