In the past six years, the Obama Administration has made a major effort to reduce the negative impact of the ways we get around on the planet, requiring major fuel economy improvements for passenger cars and trains, with planes soon to follow. Now, it's trucks' turn to slim down.

Last week, the EPA and National Highway Traffic Safety Administration announced new proposed fuel economy standards for medium- and heavy-duty vehicles—everything from the biggest pickup trucks to UPS vehicles to the semis that rule the right lane—aimed at significantly improving fuel economy in the next decade.

The current standards for these vehicles were introduced in 2011, and take effect this year, requiring a 20 percent reduction in fuel consumption. The newly introduced "phase two" rules apply to semi-trucks, large pickup trucks, vans, and buses built between 2021 and 2027. They'll have to cut another 24 percent, based on the 2018 numbers.

Trucks are incredibly important to the economy, so we're not getting rid of them anytime soon. Adie Tomer, associate fellow at the Brookings Institution

That gives truck manufacturers six years to make major fuel economy improvements. That's not as hard as it sounds. "They are easily achievable," says Noël Perry, an economist who specializes in transportation and logistics. And we already know how to get there.

We Need These Changes

Transportation is responsible for 28 percent of the nation's carbon emissions, second only to power plants at 31 percent. By nearly any measure, trucks play an outsized role in contributing greenhouse gas. They comprise just 4.3 percent of vehicles in the US, drive 9.3 percent of all miles driven each year, yet consume more than 25 percent of the fuel burned annually.

The new standards would save us $170 billion at the pump, the EPA says, and cut CO2 emissions by one billion metric tons. That's nearly the equivalent of all the greenhouse gas emissions US residences generate in a year. But trucking is a $700 billion industry that moves between two-thirds and three-fourths of the nation's freight from Point A to Point B.

"They're incredibly important to the economy, so we're not getting rid of them anytime soon," says Adie Tomer, an associate fellow at the Brookings Institution.

The good news is the trucking industry is what Tomer calls a targeted group—there aren't many players to work with, and everyone shares similar interests. You have the manufacturers and the fleet operators, so you don't have to convince a vast swath of the population that these changes are for the better. "Targeting them really can help get the biggest bang for your buck right now," Tomer says.

We don't need exotic technology to do this. Noël Perry, transportation economist

Even better, the big truck makers—folks like Daimler, Volvo, and Mack—are already working on this stuff. That's because there's a direct relationship between how much fuel you burn and how much money you make. Not only are they OK with proposals, they're already exceeding the requirements proposed by the feds. (Which begs the question, should the standards be more aggressive? But we'll leave that alone for now.)

The Easy Fixes

One of the easiest ways to improve efficiency is to make the trucks more aerodynamic. Out on the highway, where trucks spend most of their time, most of the fuel a truck burns is going toward overcoming wind resistance.

"We don't need exotic technology to do this," Perry says.

Today's vehicles are far slicker than those of the past, with things like side skirts and the ATDynamics' "Trailertail," which fits to the back of a trailer to improve stability and cut wind resistance. There's room for improvement: rounder edges, lower noses, smaller gaps to smooth the airflow, particularly between the tractor and trailer. Perry says one "laughably easy" change would be replacing those huge mirrors with tiny cameras—which would have the added benefit of providing a better view to the rear and sides. The technology exists; it's a matter of getting the feds to approve it.

New tires help, too. Rolling resistance is another drag on efficiency. That's why companies like Michelin favor using a wide tire in place of two narrower ones, as is common today. Michelin says its X One wide single tire can cut fuel use by 10 percent through reduced resistance and weight.

Volvo

Truck manufacturers can keep working on engines, too. The technology is mature, Perry says, but given the time before the new standards kick in, making them more efficient "is well within their limits." Regenerative braking could recapture energy otherwise lost as heat during braking and feed it to the battery—which powers stuff like the climate control and radio—should be more common. Smarter automatic transmissions can make even crummy drivers as efficient as the very best.

Down the Road

Those changes alone should be enough to meet the 24 percent improvement mark, Perry says, but there's another big idea out there, one that's already become mainstream in passenger cars: alternative new powertrains.

A battery-electric rig isn't feasible yet, nor are hydrogen fuel cells. The costs and range issues simply don't work in long-haul applications. But hybrid technology is already coming to medium-duty vehicles that haul things in urban areas. Delivery vehicles are a natural for electric power, because they tend to follow fixed routes, return to a common location (making charging and snap), and the torque provided by an electric motor is great for stop-and-go traffic. Market research company Navigate says global sales of fully and partially electric commercial vehicles will rise from less than 16,000 in 2014 to nearly 160,000 in 2023.

"Hydraulic hybrid" trucks recapture energy from braking and store it in a high-pressure accumulator, which can run the vehicle with the engine off, saving fuel. This technology is becoming more common, with UPS as an especially big fan. More traditional hybrids are also in the works, but not common yet.

Hydrogen fuel cells could eliminate the need for burning diesel on the highway, but the issues that have so far made them a non-starter for passenger cars still apply: Hydrogen fuel is hard to find and transport, and its production can itself yield greenhouse gases. Those problems need to be solved before that's a viable solution.

Beyond the Truck

There are ways to reduce the impact of the trucking industry that go beyond EPA standards for individual vehicles.

One is to make the things bigger, and use fewer of them, which would also help alleviate the growing driver shortage. A 2009 study by consulting group Informa Economics found increasing the truck weight limit from 80,000 to nearly 100,000 pounds could cut US long haul trips by nearly 20 percent, saving 221 million gallons of diesel, even though each individual truck would be heavier and less efficient. We could also go the way of the Aussies and allow road trains, with one tractor pulling multiple trailers, up to a total weight of more than 250,000 pounds.

It’s not just a win-win, it’s a win-win-win. You’ve got three wins. President Obama

Then there's platooning: Have one truck lead the way, with others in a line copying its every move, separated by as little as 25 feet. Like a Tour de France cyclist team, each truck in line benefits from a big drop in wind resistance. A line of five trucks could net six percent fuel savings, according to Daimler. Platooning does require vehicle-to-vehicle communication and some level of autonomous driving, but the technological solutions aren't far from reality.

Those big changes are a ways away, if they ever happen, but the incremental steps that are making trucks more efficient are already doing a lot of good. And that's important.

"Improving gas mileage for these trucks are going to drive down our oil imports even further," President Obama said last year. "That reduces carbon pollution even more, cuts down on businesses’ fuel costs, which should pay off in lower prices for consumers. So it’s not just a win-win, it’s a win-win-win. You’ve got three wins."