Rep. John D. Dingell (D-Mich.), chairman of the House subcommittee on energy and power, expressed concern yesterday that the 1985 27.5-mile-per-gallon fuel efficiency standard for U.S. cars will not be met.

"We want to identify, if we can, the obstacles to its achievement and find ways to remove them," Dingell said in opening two days of hearings on the issue. A panel of government witnesses testified yesterday, with auto union and industry representatives scheduled for today.

The industry is pushing for a change in the present schedule for efficiency targets for the years between now and 1985. It would also prefer a 26 m.p.g. standard for 1985, but apparently has decided it has little chance of achieving that change.

The National Highway Traffic Safety Administration, the Department of Energy, the Environmental Protection Agency and the Council of Economic Advisers all are studying whether the standards should be changed.

Joan Claybrook, head of NHTSA, told the subcommittee that next fall is the earliest that the standards could be changed, but that the group of agencies would reach a preliminary conclusion next month on whether they think such a change is advisable.

Meanwhile, at another House subcommittee hearing, David Bardin, head of DOE's Economic Regulatory Administration, said "it would be an outrage" if oil companies failed to meet growing demands for unleaded fuel.

"We expect them to roll up their sleeves and get the job done," he said.

Bardin's comment came as a growing number of government and industry experts are predicting shortages of unleaded gasoline this summer. He was testifying in defense of a recent rule change that will allow refiners to pass on to consumers more of their costs. The change could add 5 cents a gallon to gasoline prices this year.