A state review has found California is on track to meet its tougher car-emission standards and urges regulators to draft more ambitious environmental targets for the future.
California's Air Resources Board is expected to discuss the standards at a hearing in Riverside on Friday.
The report is a midterm review of California's car emission standards for the years 2022 to 2025 and mirrors findings by the U.S. Environmental Protection Agency under the Obama administration that the targets are appropriate.
The standards are also followed by a dozen of mostly Northeastern states, including New York and Massachusetts.
Environmental and consumer advocates say the review is critical following President Donald Trump's decision to re-examine rules governing gas mileage and establish one fuel mileage requirement for automakers across the U.S.
"It should not have been a source of conflict, but President Trump has made it a source of conflict," said Mark Cooper, director of research at the Consumer Federation of America.
Trump announced last week that the administration will re-examine rules affirmed in the waning days of the Obama administration to control greenhouse gas emissions that contribute to global warming.
Environmental groups predict Trump will weaken the standards, which now require the fleet of new cars and trucks to average 36 miles per gallon in real-world driving conditions by 2025.
The auto industry is concerned these standards will be tough to meet because people are buying more trucks and SUVs instead of fuel-efficient cars.
California started setting its own stricter pollution standards more than four decades ago to clean up the state's smoggy skies under a "waiver" from Congress.
Today, California and federal standards are currently mostly the same. However, if Trump relaxes the standards, California and the other states likely would keep the 36 mpg rule in place, potentially creating two standards. Since about 40 percent of the nation's vehicles are in states that follow California rules, automakers probably would conform to them rather than build two different vehicles for the U.S. market.
Environmental advocates say they worry the administration could seek to revoke California's waiver to create one uniform standard.
Also on Friday, the board will review a plan by Volkswagen to promote zero-emission vehicles as part of a settlement for its emissions cheating scandal. No vote is expected on that plan.
On Thursday, the board approved strict new guidelines on monitoring and repairing methane leaks at oil and gas facilities.
Detailed regulations will be instituted by state agencies, but the new rules will include quarterly monitoring for leaks and required equipment for vapor gathering.
The board says their guidelines will enhance rules for emergency-response approved by gas regulators after the massive Aliso Canyon gas leak in Los Angeles last year.