First the target was Nitrogen Oxides (NOx) that contribute to smog. Then the Particulate Matter (PM) that would otherwise burrow deep into lungs. Now regulators have set their sights on a truck’s carbon emissions.

But unlike past regulations from the U.S. Environmental Protection Agency, a series of coming standards will deliver better fuel economy.

The first round of the standards to apply to medium- and heavy-duty trucks will affect 2014-18 models years. And depending on the vehicle configurations, manufacturers will need to lower greenhouse gas emissions between 10 and 23% when compared to 2010 models that lack any of the related improvements. That translates directly into lower fuel bills.

The enhancements will be linked to factors like aerodynamic shapes and fairings, fuel-efficient tires, lighter weights, speed limiters, and controlled idling – all of which will lead trucks to generate lower levels of carbon dioxide, nitrous oxide, methane and hydrofluorocarbons. By some estimates, that will add about $6,000 to the price of the basic 2010 truck without the changes.

The improvements can largely be met with options that are available today, effectively pulling technology off the shelf and putting it onto new trucks. Many were outlined in a final report by the National Academy of Sciences, which was unveiled in March 2010, just a couple of months before U.S. President Barak Obama called on the EPA and the National Highway Transportation Safety Administration to develop the standards.

Equally as important are the things that the regulations have left untouched: Transmission gear ratios, drive axle gear ratios, engine power ratings, torque curves, tire sizes and final drive ratios can all be dictated by fleet buyers. “We want fleets to continue to make these decisions based on their actual operations, not national average conditions,” the U.S. Environmental Protection Agency’s Byron Bunker said during the annual meeting of the Technology and Maintenance Council.

Trailers are exempt from the first round of fuel-efficient rules, too. “Until we have a cheap way to test trailers and test the wide variation in trailers, it will be very hard to have a regulation,” Bunker said.

The specific reductions vary from one type of truck to the next. There are nine categories covering low-, mid- and high-roof designs in Class 7 and 8 trucks, and Class 8 tractors with sleepers. The greenhouse gases from a Class 8 tractor with a low- or mid-rise roof will need to drop 10%; a Class 8 tractor with a sleeper and high-rise roof will need to reduce the gases by 23%. These differences simply account for the different operating realities. A Class 7 day cab, for example, would not have the opportunity to eliminate hotel loads that are traditionally linked to the creature comforts in a sleeper, Bunker said. And an on/off road truck that serves a farm would be unlikely to benefit from aerodynamic fairings.

The new rules promise to make some dramatic differences. In the U.S. alone, the fleet of 2014-18 trucks will during the life of the vehicles reduce greenhouse gases by 270 million metric tons, and lead to $50 billion in fuel savings (based on $3.50 per US gallon). The improvements in the trucks will cost about $8 billion, but that will still lead to $42 billion in net fuel savings, and the savings even swell to $49 billion when factors like health and welfare are considered.

Of course, the demand for better fuel economy is not driven by regulators alone. “We’re driven by customer demand,” said Al Pearson, Daimler Trucks North America’s chief-engineer – product validation engineering. The American Trucking Associations has itself been calling for fuel economy standards since 2008.

Manufacturers have some flexibility. They can use the average improvements generated by all their trucks in a particular category, and trade some of the results between different vehicle categories. (There are some exceptions. For example, they cannot use results from pickup trucks to meet the tougher Class 8 standards.) The required reductions can also be averaged over a three-year window, and some credits can be earned as early as 2013. There are even chances to earn credits for “advanced and innovative” technology.

An individual truck’s actual savings will be generated by a new Greenhouse Gas Emission Model (GEM) tool – found at www.epa.gov/otaq/climate/gem.htm. This is where manufacturers will be able to detail the savings related to drag (aerodynamic fairings), rolling resistance (fuel-efficient tires), speed (speed limiters), lighter weights and anti-idling tools. But factors such as the engine’s fuel map, the trailer, transmission, axles and drive cycles will all be predefined.

Required improvements in aerodynamics will consider the differences between low-, mid- and high-roof tractors and sleepers. Tire changes will consider the differences between single drive tires with steel, aluminum or lightweight wheels, as well as dual or steer wheels with high-strength steel wheels, aluminum wheels or lightweight aluminum wheels. Weight reductions will focus on the door, roof, rear wall and cab floor, and whether these pieces are made of aluminum or high-strength steel. Engines will also need to shut down after five minutes of idling to gain a credit for this anti-idling strategy.

Even though the technology exists today, the savings are no small task.

 “The complexity comes when you consider the number of variables,” Pearson said. A highway tractor’s drag coefficient can be affected by the sun visor, mirrors, auxiliary mirrors, bumper, chassis fairing, fairing skirts, quarter fenders, side extenders, sleeper length and roof designs. There are more than 14.5 million combinations here alone.

The individual improvements also need to be proven by testing a coasting tractor-trailer or a combination of pre-approved tools like wind tunnels, fluid dynamics and scale models. Even issues like cross winds and the vehicle’s yaw can be considered.  “It’s probably the biggest impact for my department,” Pearson said.

The industry’s computer experts are also going to be busy finding ways to calculate the changes whenever a truck is ordered. “We are not going to have a person sitting there calculating every single truck order that comes in,” he added.

Engine makers have some challenges of their own.

 “Very rarely do two customers have the same demand,” noted Dave McKenna, director – powertrain for Mack Trucks.

Still, there are gains to be found under the hood. Load-based variable power programs on a typical tractor-trailer with a Gross Vehicle Weight of 80,000 pounds will lower greenhouse gases by one percent. By increasing the “governor droop” at high and low engine speeds, smart speed controls can gain another percentage point. Smart engine cooling fans gain another one per cent because they are only used as needed, and run at a modulated speed. And an ultra low-speed engine with cruise rpms hovering around 1,100 rpm offers another 1.5 percent gain. “It’s something that can be done,” McKenna says. “It may take a little bit getting used to, but it does work.”

That’s where the larger gains come to an end. The days of a “big bullet” or a “magic elixir” that can offer improvements of three or four percent are gone, McKenna said.

But there are new areas to explore. Wasted heat, for example, could be converted into electrical energy. “You can’t call it wasted heat anymore. We’re going to try to use it,” he said. Real-time speed controls could be made possible by combining GPS equipment and telematics, effectively building a “geo-fence” around a truck. Even two-stroke engines could have a role to play.< /p>

“Puff top” speed limiters such as those mandated in Ontario may have led to long convoys between Toronto and Montreal, but they can help to meet the new goals, he added.

Each truck will need to carry a new label to identify the specific improvements that were made, and come with maintenance information to help care for everything from emission controlling equipment to the side extenders that improve aerodynamics.

Some of the changes may not even last as long as the trucks themselves. Speed limiters, for example, can be programmed to expire after the first 350,000 miles, to limit the affect on resale prices. Future buyers will also be allowed to remove fairings from trucks that are being transformed from a highway use to a drayage operation.

But the demand for better fuel economy is unlikely to go away.