As part of an accident causation study conducted at Indiana University, in-depth accident data compiled by a multidisciplinary team were reviewed to assess the accident prevention and impact speed reduction benefits of 10 different variations of radar and antilock braking systems and 12 other vehicle system innovations or improvements. The situation with respect to driver performance and the roadway environment was in effect held constant, in order to assess whether the proposed vehicle system improvements would have enabled these crashes to be avoided. The most liberal estimates of potential benefit ranged from a low of 0.5% of accidents prevented for standardization of driver controls to a high of 45.1% of accidents prevented for the most complex of the braking systems. The latter combined collision warning and automatic brake actuation capability with 4 wheel antilock brakes. Next to braking system improvements, improved brake lights were the most promising;​ these were judged to be of possible benefit in preventing up to 8.8% of the accidents reviewed. These data in combination with data on the role played by vehicle maintenance problems and failures in causing accidents, are useful in identifying ways in which the precrash aspect of motor vehicle safety can be improved.