The U.S. Department of Transportation and Environmental Protection Agency release proposed new standards for medium- and heavy-duty trucks, pulling in the previously unregulated big pickups from General Motors Co., Ford Motor Co. and Chrysler Group LLC.

The government proposes improvements in fuel-economy and carbon-dioxide emissions reduction of between 10% and 15% beginning with the ’12 model-year and culminating in ’18.

The efficiency gains are expected to cost between $1,249 and $1,592 per vehicle in ’18, the agencies say. Deliveries of heavy duties typically account for 30% of the Detroit Three’s annual pickup sales.

The agencies expect auto makers to mostly use technologies “readily available, well-known” to meet the new regulations, while others might be expected in production “over the next few years.”

The new rules affect GM’s Chevy Silverado and GMC Sierra Heady-Duty, the Ford Super Duty and Ram Heavy Duty pickups.

Since the pickups today are unregulated, the auto makers are not required to provide fuel-economy estimates, but a recent Ward’s testing of the three outfitted with diesel technology averaged 11.5 mpg (20.5 L/100 km).

The new regulations come on the heels of new corporate average fuel economy rules calling for the U.S. light-vehicle fleet to improve to 35.5 mpg (6.6 L/100 km) by 2016. Lawmakers are currently crafting rules for 2017-2025, with the possibility of ultimately demanding 62 mpg (3.8 L/100 km).