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Status Report, Vol. 44, No. 4 | SPECIAL ISSUE: CAR SIZE, WEIGHT AND SAFETY | April 14, 2009 Subscribe

Fuel economy and safety can be achieved at the same time

One reason people buy smaller cars is to conserve fuel. The price of gasoline skyrocketed last year, and there's no telling what the price at the pump might be next week. Meanwhile, the gears are turning to hike federal fuel economy requirements to address environmental concerns.

The conflict is that smaller vehicles use less fuel but do a relatively poor job of protecting their occupants in crashes. Thus, fuel conservation policies have tended to conflict with motor vehicle safety policies. But they don't have to.

"The key going forward will be for consumers and policymakers to recognize the potential conflict and make choices that serve safety as well as fuel economy. The first step is to look at the consequences of past policies and choose future ones that serve both goals instead of setting the two at odds," says Institute president Adrian Lund.

Fuel economy at the expense of safety: More than 30 years have elapsed since Congress enacted the Energy Policy and Conservation Act of 1975, which required automakers to build cars that use less fuel. The result during the first 15 or so years of this law was to improve the overall fuel economy of the U.S. car fleet by about 75 percent.

The main way automakers achieved this was by reducing car weights. For example, Chrysler stopped making big cars altogether. By 1985 cars were an average of 500 pounds lighter than they would have been without the federal requirements.

The downside was to increase fatality risk in crashes. Multiple studies document this, including Institute research comparing deaths in Ford and General Motors cars before and after they were downsized during 1977-86 (see Status Report special issue: fuel economy and safety, Sept. 8, 1990). The finding was a 23 percent increase in deaths per 10,000 registered cars.

Subsequent research documents the continuing price in terms of lives. For example, the National Research Council concluded in 2002 that 1,300 to 2,600 additional crash deaths occurred in 1993 because of vehicle weight reductions to comply with federal standards (see "Improve fuel economy without negative safety consequences," April 6, 2002).

A problem with the current structure of fuel economy standards for cars is that the target of 27.5 miles per gallon is applied to an automaker's whole fleet, no matter the mix of cars an individual automaker sells. This encourages manufacturers to sell more smaller, lighter cars to offset the fuel consumed by their bigger, heavier models. Sometimes automakers even sell the smaller — and less safe — cars at a loss to ensure compliance with fleetwide requirements.

"What's needed instead is to restructure fuel economy standards for cars the same as the government has done for other kinds of passenger vehicles," Lund advises.

In 2006 the National Highway Traffic Safety Administration adopted a fuel economy system for SUVs, pickup trucks, and vans that mandates lower fuel consumption as vehicles get smaller and lighter, thus removing the incentive for automakers to downsize their lightest vehicles to comply (see "Overhaul of federal fuel economy program serves safety too," April 22, 2006). The result is to force the auto manufacturers to use vehicle and engine technologies to improve fuel economy. By 2011 all SUVs, pickup trucks, and vans will have to comply.

However, the same plan doesn't yet apply to cars, which still are subject to a fleetwide fuel economy standard. The Bush administration proposed a size-based standard for cars, like the other passenger vehicles, but left it to the current administration to carry through. Now the Obama administration says it's boosting the fuel economy standard for cars, beginning with 2011 models, and this will be accomplished under a size-based system.

On a separate front, California officials are trying to improve air quality by setting more stringent emissions limits than the federal government requires. The state's carbon emissions limit is structured so that vehicles of all sizes would be held to a single average, which conflicts with occupant safety goals.

A U.S. Court of Appeals is considering whether federal fuel economy standards preempt California's emissions standard, and the Institute has filed a brief opposing the state. The problem, the Institute told the court, is that "the easiest, cheapest, and quickest way for automakers to meet a significant reduction in an overall fleet average of carbon emissions is to downsize to reduce fuel consumption," which costs lives in crashes. Lund adds that if a state does succeed in preempting federal fuel economy or emissions standards, it should ensure that its programs don't have negative consequences for people in crashes.

Travel speeds affect both

Setting higher federal fuel economy targets isn't the only way to conserve fuel. How about lowering speed limits? Going slower uses less fuel to cover the same distance. There's a big safety bonus, too, that's evident in the experience of the 1970-80s (see Status Report special issue: speeding, Nov. 22, 2003).

Goaded by federal lawmakers, every state adopted 55 mph speed limits on interstate highways in 1974. The impetus was the 1973 oil embargo, and the idea was to conserve fuel by slowing down motorists until automakers could build cars that use less gas. The immediate effect was to save thousands of barrels of fuel per day — and thousands of lives. In fact, highway deaths declined about 20 percent the first year, from 55,511 in 1973 to 46,402 in 1974. The National Research Council estimated that most of the reduction was due to the lower speed limit, and the rest was because of reduced travel. By 1983 the national maximum 55 mph limit still was saving 2,000 to 4,000 lives annually.

With the oil crisis a thing of the past by the middle of the 1980s, Congress lifted pressure on states to retain 55. Speed limits began going up in 1987, and so did occupant deaths in crashes. Fifteen to 30 percent increases were documented.

"The national maximum speed limit was adopted to save fuel, but it turned out to be one of the most dramatic safety successes in motor vehicle history," Lund points out. "The political will to reinstate it probably is lacking, but if policymakers want a win-win approach, this is it. It saves fuel and lives at the same time."

More good choices going forward

Another way to serve both safety and fuel economy would be to curtail the horsepower race. Only a few cars used to be capable of 300 horsepower, but now many cars match this. Average horsepower is 70 percent higher than it was in the mid-1980s, and some of today's high-performance cars surpass the power of even the muscle cars of the 1960-70s. If an automaker were forced to use engine-enhancing technology to improve fuel efficiency instead of to boost performance, safety would improve, too, because vehicles with souped-up horsepower are associated with increased injury risk.

"Drivers don't have to wait for the government to act. They can simply choose to drive slower or choose to buy cars that aren't the smallest ones available but still earn kudos for fuel economy," Lund points out. For example, the Honda Civic Hybrid and Toyota Prius, also a hybrid, get better gas mileage than the Smart Fortwo. Even the Volkswagen Jetta with a diesel engine does almost as well.

There are other ways, both individual and societal, to serve fuel economy and safety simultaneously. For example, roundabouts serve both at intersections (see "Roundabouts can be even safer with easy changes," June 9, 2008). The key going forward is to keep the potential conflict between safety and fuel conservation in mind so that policies designed to serve one don't inadvertently compromise the other.

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