District government workers who use their personal cars to do city business get paid 13 cents a mile-about half what experts say it costs to operate an average car.

The city's building inspectors, safety specialists, social workers or others who drive their own cars to inspection sites or for other official business receive the lowest mileage reimbursement rate found in a spot check of various public agencies and private employers in the area.

The highest rates in the survey were paid by the federal government and Pepco -- 18.5 cents a mile.

For several hundred D.C. workers who use their own cars, the rate has remained unchanged since 1974. Since that time, however, the cost of gasoline in the area has more than doubled.

Several local employers have reacted to the gasoline price increases by raising their mileage allowances in recent months.

Montgomery County employes received a 2-cents-per-mile increase in May, bringing their reimbursement rate to 17 cents a mile. And in July, the state of Maryland raised the rate for state employes from 14 cents to 16 cents a mile.

Rates in Arlington and Fairfax counties are restricted to 15 cents a mile by a statewide ceiling, despite an attempt by Fairfax to raise the rate earlier this year.

Rates paid by other area employers include 17 cents a mile paid by Prince George's County, Blue Cross-Blue Shield and the AFL-CIO and 14 cents a mile by C&P Telephone Co. International Business Machines said it pays 18 cents to employes who use their cars occasionally and a higher rate, which the company refused to disclose, to regular drivers.

Mike Castillo, a program analyst in the District's General Services Department, said: "Everybody has been complaining -- and rightfully so-- that they're not getting enolgh money" for using their own cars.

"It puts me in the hole financially," said John F. Jackson, a senior safety specialist for the minimum wage and industrial safety board. Jackson estimated that he drives about 2,400 miles a year in his work. "Thirteen cents is ridiculous," he said.

The American Automobile Association and federal experts estimate it costs about 26 cents a mile to operate the average private automobile that is driven a typical 10,000 miles a year. The 26-cent figure includes not just gasoline and oil but various fixed costs, such as the purchase price, depreciation and insurance that must be paid regardless of how much a car is driven.

Most employers contend their mileage rates aren't intended to fully reimburse employees for all their fixed costs.