Policy Tracker

Safer Affordable Fuel Efficient Vehicle Rule


Final Rule Issued

Rule Making Information

Position Letters

  • CALCOG Letter
  • CARB letter on transportation impacts.
  • Opposition letter
  • Automaker letter to President Trump
  • Automaker letter to Governor Newsom

California Briefing Information

CALCOG Fact Sheets

Potential Impacts: Regional Project Lists

General Information Resources for Transportation Conformity Process

Introducing the SAFE Vehicles Rule

In August 2018, the National Highway Traffic Safety Agency (NHTSA) and the US Environmental Protection Agency (US EPA) proposed the Safer Affordable Fuel-Efficient (SAFE) Vehicle Rule. The Rule holds national fuel efficiency standards for cars and light trucks at 2020 levels. It also repeals California’s higher fuel efficiency standards, which allows California to address its unique air quality challenges (that also relate to public health, housing and equity). In short, the Rule revokes California’s authority to implement the Advanced Clean Cars and ZEV mandates.

Affecting the Conformity Process

For transportation agencies, the SAFE Rule affects how California will make “conformity” determinations under the federal Clean Air Act.  California  uses a unique emissions factor model (called “EMFAC”) to demonstrate conformity. But the current version of EMFAC assumes that the state’s fuel efficiency requirements and ZEV mandate are implemented.  In Clean Air Act parlance, the EMFAC model may not meet the federal requirement to be based upon the “latest planning assumptions.”

More than 80 percent of the state’s population (see map) lives in non-attainment areas that rely on conformity determinations.

Real Consequences for California’s Transportation Agencies

Nonconformity with the Clean Air Act has consequences for regional transportation plans (RTPs), transportation improvement programs (TIPs), and transportation projects. For example, if an MPO in a non-attainment area fails to update its RTP at the required four-year update cycle, a 12-month transportation “grace period” starts; only projects in a previously-conforming Transportation Improvement Program (TIP) can continue to be authorized by FHWA and FTA.  If the MPO fails to adopt an RTP that conforms to federal Clean Air Act requirements by the end of the 12-month grace period, the MPO “lapses.”  During a conformity lapse, only certain projects can receive additional federal funding or approvals to proceed (E-76 or federal permits), until the MPO has both a conforming plan and TIP.  This impacts regionally significant roadway and transit projects (i.e. projects not-exempt from regional or project level conformity).

Here is a $133 Billion list of projects CALCOG put together that could be affected as early as October 1 if regional FTIPs cannot demonstrate conformity by October 1.


  • In August 2018, U.S. EPA and the National Highway Traffic Safety Administration (NHTSA) proposed the draft SAFE Vehicles Rule. The effect of the rule would be to California’s authority to set its own car and light truck GHG emissions standards, set zero-emission vehicle mandates, and rolls back the existing fuel efficiency standards.
  • In September 2019, U.S. EPA and NHTSA, fearing a lengthy legal battle with the state of California, split the proposed rule into two actions. This first part, published in September 2019, revoked California’s authority to set its own passenger car and light truck greenhouse gas emissions standards and set zero-emission vehicle mandates. The second part, signed Tuesday, March 31, 2020, rolls back the Obama-era fuel efficiency standards. The rule should become effective in late June.
  • Because Part One resulted in dirtier emissions from vehicle tailpipes, CARB’s emissions model, EMFAC, had to be updated to reflect dirtier cars in the future. FHWA required EPA to approve CARB’s adjustment factors before approving RTP/TIP updates and regionally significant amendments that relied on the use of EMFAC.
  • For Part One, EPA approved CARB’s EMFAC Adjustment Factors on March 12, 2020 (See attached letters).
  • CARB is in the process of assessing the impacts of Part Two.

What does this mean for transportation planning agencies?

It is too early to tell, but extreme caution is warranted. If FHWA and FTA take a similar tact as they did in Part One, this is what we can expect on June 29 (the date Part two is anticipated to be effective).  Upon that date, FHWA/FTA may lose the ability to approve conformity determinations for RTP and TIP updates, including amendments that require the use of the EMFAC model.  This limitation will remain until US EPA provides direction allowing continued use of the model.  For Part One, that process took six months from the signature of the rule to EPA approval – September 2019 to March 2020. Since there is precedent, we hope the process for Part 2 will be faster.

What this means for California

The federal rollback could increase global warming emissions by almost 15 million metric tons per year by 2025. That is roughly equivalent to putting an additional 2.8 million cars on the state’s roads for a year. Emissions of nitrogen oxides (NOx), a key smog-forming pollutant in the state, would increase to 430 tons in 2030.

Last Updated:05/11/2020