Summary: GAO found that driver characteristics far outweigh vehicle factors in predicting crashes for passenger cars. For example, the odds of a 20-year-old driver being involved in a single-vehicle, nonrollover crash was about four times as great as that of a 50-year-old. By comparison, a 4,000-pound automobile was only 1.06 times as likely to be involved in this type of crash as a 2,000 pound car. Similarly, drivers with a history of previous traffic violations were more likely to be in a crash, and men were more likely to be in single-vehicle crashes than were women. A car's weight had little effect on the likelihood of a two-vehicle crash or a single-vehicle crash that did not involve a rollover. However, light cars were as much as three times more likely to be involved in single-vehicle rollover crashes as were heavy cars. In other types of crashes, GAO found that car-size measures other than weight, such as wheelbase or engine size, were better predictors of crash involvement. GAO found similar results when it applied its methodology to crashes involving light trucks and vans.
