A NaI monitoring system was assembled and installed to provide radiological surveillance of refuse trucks destined for the sanitary landfill at Brookhaven National Laboratory. The performance of the system was tested by obtaining count rates for various gamma reference sources placed in the bed of a pickup truck parked over the detector. The system's sensitivity was documented for the various sources counted in a stationary truck as well as in a truck moving over the detector. Data analysis also determined the lower limits of detection for the system. Performance testing of the vehicular portal monitor suggest that it can detect μCi amounts of radionuclides on a truck.