The United Auto Workers union is urging its membership to quickly voice support for an increase in the corporate average fuel economy requirement that is favored by U.S. auto makers.

An amendment to the House energy bill proposed by Rep. Baron P. Hill (D-IN) and Rep. Lee Terry (R-NE) would raise CAFE to between 32 mpg (7.4 L/100 km) and 35 mpg (6.7 L/100 km) by the ’22 model year.

More importantly to auto makers, it also would assign specific CAFE standards to different classes of vehicles, such as cars, trucks and SUVs.

The Hill-Terry legislation runs against a more stringent proposal from Rep. Edward J. Markey (D-MA) and Rep. Todd Russell Platts (R-PA) that is backed by many Democrats and environmental groups, such as the Sierra Club.

The Markey bill eliminates the distinction between passenger cars and light trucks and mandates a 35-mpg CAFE standard for the combined car-truck fleets by 2018.

“This extreme, dangerous proposal is not economically or technologically feasible and would pose an enormous threat to the jobs and benefits of active and retired workers,” the UAW says in a letter sent to members Monday and obtained by Ward’s.

Although lawmakers led by Rep. John Dingell (D-MI) recently removed language for a new CAFE requirement from the House energy bill, it’s widely expected that Democrats keen to increase the average could try to push the Markey-Platts amendment onto the legislation this week.

The Senate approved in May a comprehensive energy bill that would raise the CAFE requirement to 35 mpg (6.7 L/100 km) from the current 25 mpg (9.4 L/100 km) standard by 2020.

jamend@wardsauto.com