Blog Post

Phase 2 proposal drives truck fuel efficiency forward, but engine standards need a boost

October 5, 2015

New fuel efficiency and greenhouse gas emissions standards for heavy-duty vehicles and engines, proposed this summer, have just run the gauntlet of public comment on their way to final adoption next year. As proposed, these Phase 2 standards would provide major gains in fuel efficiency for heavy-duty vehicles by 2027. The Phase 2 program will build on the success of the Phase 1 program adopted in 2011, and will help consolidate US manufacturing leadership in several advanced truck technologies in a global market. The Phase 2 program also offers the potential of new jobs in the design and production of these advanced vehicle technologies.

ACEEE, in its written comments submitted to the docket, applauds the agencies’ excellent work in developing the Phase 2 proposal. Phase 2 would improve upon the Phase 1 program in several fundamental ways, including:

  • a certification approach that better reflects the benefits of integrating engine, transmission, and vehicle improvements,
  • further vehicle segmentation and more realistic duty cycles to better capture technologies’ real-world benefits, and
  • the addition of trailers to the program (the current standards only apply to the tractor portion of tractor-trailers).

Facilitated by these advances in the program, the proposed Phase 2 standards would bring 20% and 24% further reductions in new vehicles’ fuel consumption and greenhouse gas emissions by 2024 and 2027, respectively.

Yet, there are a few missed opportunities in the current Phase 2 proposal. It should be strengthened in several areas to capture more of the available fuel savings. Greater reductions can be achieved, especially in the engines used for tractor trucks and vocational vehicles, even without accelerating or increasing reliance on advanced engine technologies such as waste heat recovery. Incremental improvements to engine, transmission, and vehicle, combined with the advanced technology adoption assumed by the agencies, can achieve 26% and 31% reductions in overall fuel consumption in 2024 and 2027, respectively, substantially more than the agencies’ proposed 24% reduction in 2027.

Given concerns that have been raised about the cost, performance and/or durability of some advanced technologies, it is worth noting that the standards proposed for 2027 could be achieved in 2024 without any adoption of waste heat recovery, advanced aerodynamics for tractors and trailers, advanced tires, start/stop systems, or hybridization.

At the same time, nudging technologies into the market is one of the main functions of efficiency standards to begin with. So standards that can be met for the foreseeable future with off-the-shelf technologies are missing a key element. Therefore, particularly if the program is extended to 2027, it is necessary to substantially strengthen the standards. That’s the only way to ensure that Phase 2 points the way to the heavy-duty truck and truck industry of the future.

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Fuel Economy Vehicle Technology


Siddiq Khan
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