This paper describes the assessment of driver interfaces of a type of electronics-based collision avoidance systems that has been recently developed to assist drivers of vehicles in avoiding certain types of collisions. The electronics-based crash avoidance systems studied were those which detect the presence of objects located on the left and/or right sides of the vehicle, called Side Collision Avoidance Systems, or SCAS.As many SCAS as could be obtained, including several pre-production prototypes, were acquired and tested. The testing focused on measuring sensor performance and assessing the qualities of the driver interfaces. This paper presents only the results of the driver interface assessments. The sensor performance data are presented in the NHTSA report “Development of Performance Specifications for Collision Avoidance Systems for Lane Changing, Merging, and Backing - Task 3 - Test of Existing Hardware Systems” .One goal of this research was to evaluate, based upon the principles of human factors, how well the driver interfaces of the SCAS studied were designed. The strengths and weaknesses of each driver interface were determined. Overall, while none of the SCAS had an “ideal” interface, most had ergonomically acceptable interfaces. Not surprisingly, the commercially available systems tended to have better driver interfaces than did the prototypes. Another goal of this research was to provide advice to future designers of collision avoidance system driver interfaces regarding ergonomically desirable or undesirable features. From the evaluations performed, a preliminary set of driver interface performance specifications that may be of aid to future SCAS driver interface designers has been developed.