CAFE standards have other effects that need to be taken into consideration as well. Generally, the standards give automakers an incentive to make cars smaller and lighter. Smaller and lighter vehicles tend to be less safe for occupants in traffic accidents. If more drivers are using these vehicles, traffic fatalities should rise. A majority of members on the National Research Council’s Committee on the Effectiveness and Impact of Corporate Average Fuel Economy Standards agreed with the estimate that reducing vehicle size and weight resulted in more motor vehicle deaths in 1993 — between 1,300 and 2,600 — that would not have happened had average size and weight remained at their 1976 levels. Mark Jacobsen estimates that there are an additional 150 fatalities annually as a result of reductions in vehicle size and weight for every 0.1 mile per gallon increase in the CAFE standard.
The safety risk stems from CAFE standards compelling U.S. automakers to sell more light trucks than passenger cars and to make their passenger cars smaller. The risk of a fatal accident increases when a smaller, lighter passenger car collides with a light truck, such as a pickup or SUV. The size and weight protect the driver of the light truck, but they inflict disproportionate damage on the smaller car.
In addition, Jacobsen finds that light trucks and large sedans are associated with riskier driving and thus an increased risk of a fatal accident. The additional fatalities from making vehicles smaller and lighter impose a $1.55-per gallon cost for every gallon of gasoline saved through CAFE standards, according to Jacobsen. Thomas Klier and Joshua Linn find that because of the reduction in the size and weight of passenger cars, light trucks impose a cost of approximately $2,000 per vehicle when the disproportionate damage they inflict in an accident is considered.