As the Environmental Protection Agency (EPA) begins to shape new emissions standards under the Biden administration, the agency is also taking a second look at its rulemaking under the Trump administration—and it's finding flaws.

An agency statement released Tuesday expressed "concerns" about the process used to create the so-called Safer Affordable Fuel-Efficient (SAFE) rule, which sets a lower bar for efficiency improvements between 2021 and 2026 than rules laid out by the Obama administration.

After an audit of the SAFE rule—which was announced last March and went into effect June 29, 2020—the EPA Office of the Inspector General found that development of the Trump-era emissions targets "bypassed aspects of the EPA's normal rule-making process."

This included skipping internal "Action Development Process milestones," not documenting who decided to skip those milestones and why, and relying solely on analysis from the National Highway Traffic Safety Administration (NHTSA). The two agencies jointly issue new emissions rules, but in this case the EPA did not conduct its own analysis, breaking protocol.

The initial document also had “numerous errors and inaccuracies” when it was submitted for interagency review, the inspector general said—and yet it was signed by Administrator Andrew Wheeler, with many that needed to be corrected after he signed. EPA staff warned of these issues as the rule was being drafted, The Hill reported.

Bugatti Chiron Super Sport 300+'s 3D-printed exhaust shield

Bugatti Chiron Super Sport 300+'s 3D-printed exhaust shield

Many of the procedural violations were also highlighted in a February 2020 memo from Senator Tom Carper to the EPA inspector general, the Environmental Defense Fund noted in a statement on the audit.

The EPA is expected to take action about the SAFE rule, but it's not yet clear whether that means a completely different policy or an amended version of what was passed—perhaps with an electric-vehicle mandate, in line with the Biden administration's stated plans to emphasize EVs.

The rule replaced 5% annual increases in fuel efficiency set by the Obama administration with a 1.5% annual target from 2021 through 2026. That was somewhat of a concession by the Trump administration, which originally planned to freeze fuel-economy standards at 2020 levels through 2026, as well as revoke California's ability to set its own higher standards. It was surprised that automakers didn't want that outcome, as it went against corporate sustainability targets and global portfolios shared with rapidly electrifying Europe and China.

The agencies took a long time to move through a rule-making process that still skipped many steps, and in the meantime some automakers cut side deals with California. The effort targeting California petered out after the 2020 Presidential election, with automakers supporting it gradually dropping out of a lawsuit against the state.

EPA administrator Michael Regan said in an interview earlier this month that tougher emissions standards will be announced in July.