:The demands, imposed by trailer towing, lead to dynamic driving problems and problems of operating strength. This paper is intended to describe the varied and extensive development work needed.Dynamic driving considerations show that instability (or snaking) is incurred as a result of disturbances acting on the car and trailer combination, for example lane changes, load-reversal reactions and gusts of wind from the side. The damping process decreases with road speed. Damping is obtained by using a friction damper or by using a trailer coupling with virtual towbar extension.The body testing with particular reference to trailer towing commences with the recording of relevant data. To get an idea of customer behaviour it was additionally decided to conduct a customer survey. After processing, these data are used to design operating strength test rigs.In the case of body testing a 16 channel combined body/trailer coupling test rig is used. In addition to these costly tests a simple substitute test as close as possible to actual operating practice was created, in order to aid the supplier's development work, and to assure quality control at the car manufacturer.