Passenger cars have become smaller and lighter over the past two decades, and have lower, more aerodynamic frontal shapes. Traffic barriers, however, have changed little since current systems were developed in the 1960s. There is growing concern that changes in vehicle characteristics will adversely affect barrier performance, resulting in decreased protection for occupants of modern cars. This paper compares current vehicle frontal geometry to typical 1960s geometry. In addition, examples of barrier accidents in which vehicle characteristics contributed to severe results are discussed.To determine how performance is affected by vehicle characteristics, a data base consisting of 3300 barrier accidents was compiled, covering the period from July 1982 through June 1983. This paper discusses the affects of vehicle size, weight, and model year on accident severity. In addition, accident severity involving vehicle models with low frontal profiles was examined. Based on this analysis, it appears that better barrier performance is achieved for newer vehicles, and automobile size and weight does not substantially affect barrier performance. However, this accident sample included few current vehicles with low frontal profiles, and some of the concerns relating to such vehicles thus could not be examined.