A promise of lower fuel use has both household and environmental appeal, but a forecast should not be reported as an accomplished benefit. EPA and NHTSA's Phase 2 final rule, published October 25, 2016, sets standards for new medium- and heavy-duty vehicles and engines. Its benefits discussion projects fuel savings and emissions reductions from a program still ahead of implementation. [2016-21203][2015-15500]

The rule is effective December 27. Its final requirements phase toward model year 2027, with intermediate standards in 2021 and 2024 and EPA standards for certain trailers beginning in 2018. Those dates help explain why publication is not a moment at which the modeled gains have already been achieved. The rule describes future vehicle performance, not a completed environmental accounting. [2016-21203][2015-15500]

The July 13, 2015 proposal also presented expected savings and costs while inviting examination of its design. The final rule says the program changed following further analysis and information. Using the proposal as historical context is useful; treating its estimates as final results is not. The documents belong to one EPA–NHTSA process, not independent measurements of benefits received by communities. [2016-21203][2015-15500]

Our stewardship reading is that projections can inform a decision without becoming guarantees. The final framework allows different technology combinations and distinguishes vehicle categories, so a broad national estimate cannot establish one operator's payback. A fair account keeps the intended public gains beside implementation costs and uncertainty. Whether the expected benefits reach people and reduce emissions would require later evidence, not confidence borrowed from the act of issuing a rule. [2016-21203][2015-15500]

Source documents

  1. Greenhouse Gas Emissions and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and Vehicles-Phase 2https://www.govinfo.gov/content/pkg/FR-2016-10-25/html/2016-21203.htm
  2. Heavy-duty vehicle Phase 2 proposalhttps://www.govinfo.gov/content/pkg/FR-2015-07-13/html/2015-15500.htm