This paper presents the results of a comparison between testbed and road testing for various engine related test procedures. The development of engines and engine management systems for passenger cars and light duty vehicles requires extensive testing. Very important is the behaviour of the engine/vehicle combinations at extreme cold ambient temperatures, which are defined by our customers. Unfortunately, the time period during the year when one can consistently find these temperatures is very limited and in most cases the time period is much too short to conduct all the necessary tests. Therefore a large part of the testing has to be done on a testbed (cold chamber with dynamometer).