The Safety Impact of Increasing Automotive Fuel Economy Standards
The debate over higher CAFE standards is defined by the trade-offs that consumers would be forced to accept if the standards were raised. Chief among these trade-offs is the decline in highway safety that would follow CAFE increases. Safety and fuel economy are closely linked because both are connected to vehicle size and weight. The increased safety risk is the cause of great concern and controversy.
Countless studies show that larger and heavier vehicles, all other things being equal, are safer than smaller and lighter ones. Vehicle weight and size are critical factors in determining a vehicle's crashworthiness (that is, its ability to absorb the energy in a crash and still protect its occupants) and stability.
To illustrate the relationship between size and safety, the Insurance Institute for Highway Safety (IIHS) studied the occupant death rates of 11 car models that had been downsized since 1977, comparing performance before and after downsizing. It found that death rates were higher for 10 of the 11 vehicle types after downsizing. The new, smaller, lighter versions of these vehicles were averaging 23 percent more deaths than their earlier counterparts. A recent IIHS study found that even when equipped with air bags, smaller cars are still less safe than larger cars.
Source: Insurance Institute for Highway Safety.
IIHS has stated, "Researchers have known for years that people in small cars are injured more often and more severely than the occupants of large cars. Small cars have less structure, mass and size to absorb crash energy, so more injurious forces can reach their occupants in crashes."
Vehicle size and weight are clearly related to safety and to fuel economy. Looking at EPA fuel economy ratings, it is clear that those vehicles with the highest ratings tend to be smaller, lighter vehicles, while larger, heavier vehicles tend to have lower ratings. This should come as no surprise because, as the NAS noted, "one of the most direct methods automakers can use to improve fuel economy is to reduce vehicle size and weight."
History gives us an indication of what to expect: Auto experts estimate that almost 50 percent of the fuel economy gains made since the mid-1970s are attributable to reductions in vehicle size and weight. The average car today is 1,000 pounds lighter than the average car in the mid-1970s.
Has there been a safety cost to downsizing? In 1991, the National Highway Traffic Safety Administration (NHTSA), the federal agency responsible for highway safety, concluded that vehicle downsizing since the mid-1970s was responsible for an additional 2,000 deaths and 20,000 serious injuries on our highways every year. Why? Because smaller cars are more prone to roll over than larger cars. In fact, two-thirds of the increased fatalities come from rollovers and smaller cars have less crush space than larger cars. Some have argued that if all cars on the road were smaller, there would be no increase in fatalities and injuries. But NHTSA found that a collision between two small cars is more likely to result in serious injuries than in a similar collision between two large cars, by almost 10 percent for a 1,000 pound weight reduction.
The American judicial system has also found that increased CAFE standards pose a safety hazard. In 1992, a federal appeals court found that NHTSA had not sufficiently considered the safety impacts of higher fuel economy standards. The court concluded that... "By making it harder to buy large cars, the 27.5 mpg standard will increase traffic fatalities if, as a general matter, small cars are less safe than big ones. They are, as NHTSA itself acknowledges."
Further downsizing would have a grim impact on future highway safety progress in the United States. Increased safety belt use, further reductions in drunk driving, and new safety technologies such as air bags and anti-lock brakes hold the promise of a continuing decline in annual fatality and injury statistics. But a severe CAFE increase that results in vehicle downsizing could jeopardize this progress.
A study by John Graham of the Harvard Injury Control Center found that an increase in CAFE to proposed levels (40 mpg for cars) would result in downsizing that would produce an additional 1,650 deaths and 8,500 serious injuries on U.S. highways every year. Thus the trade-off: Should policymakers ask Americans to accept higher safety risks for a few more miles per gallon?
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updated: 8/24/97 |
