Informing Consumer Choices
Since passage of the National Traffic and Motor Vehicle Safety Act of 1966, which created the agency known today as NHTSA, establishment of motor vehicle safety standards has been a primary emphasis of federal policy. Numerous such standards have been introduced, including those mandating collapsible steering columns, nonlacerating windshields, safety belts, and air bags. Although the role played by each of these individual measures cannot be determined precisely, the rate of motor vehicle fatalities has declined by 70 percent since 1966. Yet an annual toll in excess of 40,000 highway deaths suggests that more can be done in the area of vehicle safety. 
Mindful of the growing interest in motor vehicle safety features and the federal role in automotive safety, Congress requested a study of related consumer information needs in 1994. Consumers have increasingly been demanding and paying for more vehicle safety features, such as antilock braking systems and air bags. Consumer magazines, such as Consumer Reports, provide safety information about vehicles, and a prominent television program even features the crash test results of the Insurance Institute for Highway Safety. The strong and growing consumer interest in safety indicates that the government could influence which vehicles and vehicle features consumers seek out to provide for their own safety.
Perhaps the most common question consumers ask is which car is safest. Unfortunately, there is no good answer to this question. Many vehicle, driver, and roadside features influence crash outcomes in ways that are difficult to predict. A 1996 TRB committee concluded that the federal government could facilitate progress toward an overall measure of vehicle safety by investing in research and by working with experts in academia and industry (Special Report 248: Shopping for Safety: Providing Consumer Automotive Safety Information; TRB 1996). Because of the complexities involved and the current lack of adequate data on many salient variables, however, achievement of such a goal would take many years. In the nearer term, NHTSA could do much to improve the quality of existing information and convey it to consumers more clearly and efficiently. For example, the agency could give consumers a better understanding of the importance of vehicle dimensions for safety outcomes, the benefits of proper use of vehicle safety features, the frequency of crash types for which tests exist, and the uncertainties associated with crash tests themselves.
Following NHTSA’s issuance of vehicle ratings to inform consumers about rollover risk, Congress requested a TRB study to evaluate the appropriateness of the rating system. Motor vehicle rollovers involving passenger cars, vans, pickup trucks, and sport utility vehicles result in approximately 10,000 deaths and 27,000 serious injuries each year in the United States. NHTSA developed a five-star rating system to inform consumers about the rollover resistance of passenger cars and light-duty passenger vehicle trucks. 
After thoroughly evaluating NHTSA’s development of the rating system, the committee that conducted this study concurred with the agency’s reliance on a static measure of vehicle stability but pointed out some inadequacies of the statistical model used to relate this static measure to rollover risk (Special Report 265: The National Highway Traffic Safety Administration’s Rating System for Rollover Resistance: A Review; TRB 2002). Alternative statistical approaches would provide a better approximation of risk. The rating system itself was found wanting. The procedures used to develop and test the ratings with consumers through focus groups did not provide credible evidence that consumers understood the message about the actual risk associated with a given vehicle. By being limited to only five levels, the system also discarded valuable information. The data developed by NHTSA could be refined to enable consumers to discriminate better among vehicle models with regard to their rollover experience.