This paper presents the results of wind tunnel experiments in which force and moment data were measured for a variety of passenger and recreational vehicles in the presence of an intercity bus and a tractor plus semitrailer truck. The disturbed vehicles studied include a sedan, station wagon, compact sedan, van, truck/camper, and station wagon towing a trailer.A description of the apparatus is given along with details of the scale models used. Basic lateral-directional aerodynamic data for the passenger vehicles alone are shown for yaw angles up to 105 deg. Force and moment data for the vehicles in the presence of the disturbing truck or bus are shown for varying lateral separation and longitudinal positions of the two vehicles, as well as the relative crosswind angle. Critical conditions for a large disturbance due to a truck or bus are discussed.