ORLANDO, Fla. — Time is running out to comment on the joint EPA/NHTSA greenhouse gas Phase 2 regulations, which were proposed in June and set to go into effect on 2021 model year trucks.

The official comment period will end Oct. 1, at which time the Environmental Protection Agency and National Highway Traffic Safety Administration will review input from stakeholders and make any necessary amendments to the regulation. The final rulemaking will be released in the second quarter of 2016.

The proposed rule calls for fuel economy improvements of: 4% from the engine; 8% from trailers; 24% for tractors; and 16% for vocational trucks, compared to a 2017 baseline. The improvements will be phased in between 2021 and 2027 model year trucks, with trailer improvements set to begin in 2018.

“The long lead time is extremely important to ensure reliability and durability,” EPA representative Matt Spears told attendees at the Technology & Maintenance Council’s fall meetings here this week.

He acknowledged the Phase 2 requirements are “more aggressive” than the Phase 1 regulations, which were met using mostly off-the-shelf technologies already in widespread use. As with the previous round, truck manufacturers will choose which technologies to employ. They could include: engine, transmission and driveline improvements; weight reductions; engine start/stop technologies; low rolling resistance tires; aerodynamic devices; waste heat recovery; reduced friction within the engine; and improved emissions aftertreatment systems.

The cost of complying will likely add about 12% to the purchase price of a new highway truck, Spears acknowledged. Trailers and vocational trucks are likely to climb in price by 5%. However, Spears said model year 2027 tractors will deliver an ROI in their second year of use due to improved fuel economy, with vocational trucks delivering a payback in their sixth year.

“We see this as an opportunity to bring down the costs of transporting freight, benefiting business and consumers,” Spears said, noting US$170 billion in fuel savings is expected to be achieved over the life of the vehicles sold under the program. Spears also noted the Phase 2 standards will move the US ahead of Europe in terms of emissions reductions from heavy vehicles.

Jason Johnson of Kenworth said, “There will be technologies on trucks we have not seen yet.”

Charlie Fetz of Great Dane Trailers, said his company is still studying the regulation to determine how it will meet the requirements. Low rolling resistance tires, tire inflation systems, weight reductions and aerodynamic fairings are likely to be employed.

“Some people may be forced to buy things they don’t want to, such as aerodynamic options or low rolling resistance tires,” he said, noting items like tires and aero devices will be considered part of the trailer’s emissions equipment and will have to be maintained.

In the early stages of the program, dry vans will need low rolling resistance tires and either skirts or trailer tails to comply. By 2027, they’ll likely need both side skirts and trailer tails and possibly even more, Fetz said.

Certain trailer types will receive exemptions or be excluded from the rule altogether. For example, tankers won’t require trailer tails and log trailers and cattleliners won’t have to comply at all. Rulemakers are still working to define heavy-haul for the purposes of the rule, so there could be some leeway afforded there, Fetz added.

The EPA’s Spears also provided some clarity on how gliders will be affected by the new rules. He said gliders themselves won’t be outlawed, but OEMs will have to install in them engines that meet current emissions standards. There’s an exception for small businesses that sell only gliders; they’ll be allowed to continue selling a limited number of gliders with pre-emissions engines.