A simple procedure was developed for the estimation of road vehicle aerodynamic drag based on easily quantifiable vehicle shape parameters. The procedure is applicable to passenger vehicles, station wagons, and vans and is based on a 'drag build-up' method which includes the effects of the basic body shape, underpanning, and cooling drag. Not included are effects of lift, sidewind, ground clearance, and certain shape details. The limitations of the procedure are discussed and improvements and areas requiring further study are identified. In a related activity, a brief investigation was made of possible techniques for determining vehicle frontal area from photographs of cars. Planimeter measurements of frontal area were made from photographic enlargements of approximately 80 cars. The results of this effort are included as an appendix. Bibliographies on road vehicle aerodynamic drag and on wind tunnel and full-scale road testing techniques are also appended.