Try tuning in to next week's public hearings on the federal government's first-ever efficiency standards for medium- and heavy-duty trucks, where—surprisingly—it looks like all sides will be singing the same tune. Truckers like it, truck manufacturers like it, scientists like it, environmentalists like it . . . which should leave you wondering why the government needs to get involved at all.

The first thing to understand is that, while the new rules are being billed as anti-greenhouse-gas measures, in practice that translates to fuel-efficiency standards—something that President Bush's 2007 Energy Independence and Security Act had already committed to for heavy trucks. The trucking industry feared that President Obama's pledge to tackle its greenhouse gas emissions might translate into an across-the-board gas tax, or the mandatory adoption of specific emissions-reducing technologies. So the decision to regulate emissions by piggybacking on fleet-wide fuel-efficiency standards, leaving manufacturers plenty of flexibility, came as a relief.

The real question is, why have big rigs been exempt from standards for so long? After all, the corresponding rules for passenger cars and light trucks were passed back in 1975, in the wake of the Arab oil embargo, and first came into effect for 1978 model years. If you have any doubts about whether these rules made a difference, this Department of Energy data, which shows the mpg rise of passenger cars, vans, pick-ups and SUVs next to the static fuel economy of heavy-duty trucks, should dispel them:

And efficiency-impaired heavy trucks are by no means a minor part of the fuel-use and emissions picture. "These trucks represent only 4 percent of vehicles on the road, but they consume 20 percent of the fuel," Union of Concerned Scientists analyst Don Anair points out. They also contribute 6 percent of total U.S. greenhouse-gas emissions—and, crucially, they're the fastest-growing segment of the transportation sector.

The problem is that trucks are complicated: the new rules apply to pretty much everything over 8500 pounds, from the semis that pull long-haul trailers to school buses, fire trucks and pickups. A delivery truck that spends most of its time on the highway needs different rules from a garbage truck that stops every 10 yards. And "miles per gallon" is meaningless when you're hauling different loads. The new rules rely heavily on recommendations by a National Research Council report released earlier this year to divide trucks into three basic categories, and express the fuel standards as "gallons per thousand tons per mile" to take load into account.

Costs and Benefits

The standards will be phased in gradually for the 2014 to 2018 model years, and they'll improve fuel efficiency by between 7 and 20 percent, depending on the truck type. That will save 500 million barrels of oil and 250 million metric tons of greenhouse gas, according to EPA calculations. The cost to implement the needed changes: $7.7 billion. The resulting benefits: $49 billion. Even if you ignore fuzzy concepts like "societal benefits," the fuel savings alone are expected to add up to $35 billion.

For individual trucks, the rules will typically add $200 to $400 to the sticker price of a 2014 model. Long-haul truckers will see larger hikes, projected at $5900 on average, but will end up saving $74,000 over the life of the truck.

That's the kind of promised return on investment that usually gets flagged by your spam filter, so it's worth asking whether the technology projections are realistic. As it turns out, you don't even need projections: the American Trucking Associations say the new standards will be largely met with "off-the-shelf technologies such as low-rolling-resistance tires, improved aerodynamics [and] reduced idling." The EPA already has a voluntary SmartWay certification that encourages truckers to adopt these measures, which can be as simple as narrowing the gap between tractor and trailer to reduce drag.

With standards so easily met, you'd expect environmental groups to be disappointed. The Union of Concerned Scientists does point out that, if the rules applied to trailers as well as trucks, big-rig fuel efficiency could easily be hiked by 35 percent rather than just 20 percent by 2017. But overall, most environmental groups seem pleased.

Instead, one of the few critical notes comes from Heavy Duty Trucking magazine. "Legislating fuel economy standards for truckers is like requiring bears to crap in the woods," one of its writers notes. "I'm thinking this first round of reductions is just to get us primed for what's to come."

Interestingly, the National Research Council report made a related point back in March:

"The choices that will be made over the course of the next few years will establish the regulatory design for [mid-size- and heavy-truck] fuel-consumption standards for the next several decades at least. While the stringency of the standards themselves may be revisited from time to time, the regulatory design elements (regulated parties, certification tests and procedures, compliance methods)—once established—are far more difficult to modify."

So we could haggle over the numbers if we really wanted to—whether the gas savings will really total $35 billion or whether they'll be just half that, whether the costs will be higher than forecast, and so on. But it's hard to escape the feeling that the specific numbers aren't really the point, at least this time round. That's why there will be so little bickering at next week's hearings: efficiency standards for heavy trucks were long overdue, and the interested parties have managed to hammer out a basic format that everyone can live with. The standards may be soft (for now), but their greatest significance is simply that they exist.

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