General Motors Corp. yesterday said it will raise prices on its 1985 cars by an average 2.3 percent over comparably equipped 1984 models.

The boost is in line with predictions by auto industry analysts, who had expected domestic manufacturers to raise their new-car prices by an average rate of 2 to 4 percent.

The inflation rate as measured by the consumer price index -- which monitors changes in the costs of goods and services -- is running at about 4 percent.

GM says the higher prices will give it 2 percent more in annual revenues "for the partial recovery of ongoing increases in the cost of material, labor and services," and 0.3 percent more to help recover "product improvement incorporated in many models to improve fuel economy and reduce exhaust emissions."

GM did not give details on how the price increases will affect specific models. The company also said nothing about what will happen to the prices of its 1985-model trucks.

However, analysts and other industry sources believe GM will follow its pattern of previous years -- holding down, or perhaps even rolling back, prices on some of its slower selling cars, such as the embattled X models, and boosting prices on its hot-selling models, such as the two-seat Pontiac Fiero.

Buyers of GM's big cars can also expect to pay substantially higher prices. Both GM and its largest domestic rival, Ford Motor Co., are under federal pressure to meet corporate average fuel economy (CAFE) standards that establish minimum new-car fleet fuel consumption ratings, measured in miles per gallon.

Auto makers failing to meet those standards -- 27.5 mpg for 1985 -- will be hit with federal "gas-guzzler taxes," which will be passed on to buyers of big cars.

The 1983 CAFE standard for passenger cars was 26 mpg. GM ended the year with a CAFE of 23.5 mpg and Ford finished with 23.8 mpg. Both companies are trailing the 1984 standard of 27 mpg.

Diane K. Steed, administrator of the National Highway Traffic Safety Administration, which monitors CAFE compliance, said in Detroit this week that her agency sees no need to reduce CAFE requirements to help Ford and GM.

Ford has yet to announce its 1985-model car prices. But the company has sent letters to its dealers announcing price increases on its 1985-model light trucks ranging from 1 to 4 percent.

Chrysler Corp., the nation's third-largest auto maker, has announced tentative price increases averaging 4.1 percent on its popular minivans and trucks. Chrysler said its new-car prices probably will increase an average 1.7 percent, or $181.

American Motors Corp., the fourth-largest U.S. car maker, says prices will rise an average 2.3 percent on its AMC/Renault Alliance and Encore cars and about 4.1 percent on the AMC Eagle and Jeep models, compared with similarly equipped 1984 models.