Improving gasoline fuel economy and strong demand for trucks and SUVs has led federal regulators to eliminate the 54.5 mpg corporate fuel economy target for 2025.

The U.S. Environmental Protection Agency, National Highway Traffic Safety Administration, and California Air Resources Board released their Technical Assessment Report that drives adoption of fuel efficiency requirements for vehicle manufacturers.

Vehicle manufacturers have been facing increasing fuel efficiency requirements for their vehicles from a 2011 agreement to lower emissions from vehicles. The 2017-MY represents another stair-step higher with larger pickups such as the F-150 needing to average 25 mpg and smaller cars needing to average 44 mpg.

The draft report, which will now draw public comment before final approval, acknowledges that gasoline-powered vehicles will remain the norm rather than battery-electric cars or hybrids. To meet future standards, manufacturers will need to develop "modest levels of strong hybridization and very low levels of full electrification (plug-in vehicles)."

Rather than achieving fuel efficiency gains though electrification, which won't play a major role by 2025, automakers will likely reduce emissions with more efficient internal combustion engines that use technologies such as "turbo charging, engine downsizing, more sophisticated transmissions, vehicle weight reduction, aerodynamics, and idle stop-start, along with improved accessories and air conditioning systems."

More than 100 models of cars, SUVs or pickups being sold today already meet the 2020 or later standards, according to the EPA.

The tilt toward trucks and SUVs "reflects updated consumer trends that are informed by a range of factors including economic growth, gasoline prices, and other macro trends."

The report focuses on the 2022 to 2025 model years. The public may provide comments for 60 days, and the EPA will make a final determination by April 1, 2018.