In this paper, we describe the results from a series of experiments using the 'virtual bumper' collision avoidance algorithm implemented on a Navistar International tractor cab. The virtual bumper combines longitudinal and lateral collision avoidance capabilities to control a vehicle in both normal and emergency situations. The motion of the vehicle is modified based on sensed incursions into a programmable 'personal space' around the vehicle. An impedance controller determines the dynamics of the vehicle response. Radar integrated with a laser finder are used to sense vehicles in the forward field of view of the host vehicle. The results of two driving scenarios are presented. The first scenario tests the system's ability to stop the tractor at a safe headway in response to a stationary vehicle. The second scenario demonstrates the Adaptive Cruise Control (ACC) functionality implemented using the virtual bumper. In this scenario, the test vehicle is able to safely stop when the preceding target vehicle suddenly decelerates to a stop. The system has been successfully tested in a variety of other situations as well. The virtual bumper proved effective in ACC scenarios, major traffic slow down situations, sudden target acceleration/deceleration and in stop and go traffic.