Recommended passenger car size definitions and the need for vehicle identification in traffic accident data.

Car downsizing has continuously altered the concept and definition of car size. A new set of standard car size definitions detailed in the paper has been recommended that provide for either three weight categories or three wheelbase categories. Each classification can be split into six categories or both can be combined into a nine cell cross-classification. It is also recommended that all traffic records retain the original vehicle identification number and actual vehicle weight and wheelbase, for use in classification and analysis.