U.S. Environmental Protection Agency (EPA) chief Andrew Wheeler is sending signals that the Trump administration's plans to roll back Obama-era fuel-efficiency standards may not go forward as originally outlined. According to Wheeler, "key aspects" of the strategy are still under review.

Wheeler told Bloomberg that while the administration remains committed to rolling back the standards implemented under President Obama, "it's safe to say our final will not look exactly like the way we proposed it."

And while Wheeler said that moving forward with a plan to revoke California's authority to set its own requirements is "still an option," the administration has not yet committed to it. 

California has become an obstacle to the Trump administration's ambitions for slackening fuel efficiency standards in several distinct steps. Several major automakers—Ford, Volkswagen, BMW, and Honda—along with 23 states volunteered to adhere to California's emissions reduction schedule rather than supporting the president's rollbacks. 

The U.S. Department of Justice announced it would investigate those automakers to determine whether they colluded in making that decision in a way that would violate federal antitrust laws. Since, the administration has been working to nullify California's authority to set its own emissions standards entirely

The administration originally outlined a plan that would call for capping fuel-efficiency standards at a level equivalent to about 37 mpg in real-world measurement. Officials justified the reversal of the previous policy by saying it would reduce the cost of new cars, giving consumers more flexibility to purchaser newer, safer vehicles rather than holding on to older ones.

Both the policies laid out in the proposal and the rationalizations behind them were almost instantly called into question when it was first unveiled, and while it appears the administration is willing to go to great lengths to see it implemented, it remains to be seen just how much leeway it will ultimately have.