This SAE Recommended Practice is intended to provide uniform nomenclature and definitions for the primary levels of vehicle identification, with particular application to passenger cars.

While this initial terminology applies only to passenger cars, work is in progress to develop supplementary nomenclature and definitions pertaining to truck and/or commercial vehicle terms and terms presently used interchangeably in passenger cars, trucks, or commercial vehicle applications. These supplementary terms will be covered in subsequent revisions to this recommended practice.