DETROIT -- The cost of owning and operating a typical new compact car in 1987 rose 5.5 percent to a record $5,114 a year, according to an annual study released by Hertz Corp. yesterday.

The giant rental and leasing company said overall car ownership and operating expenses rose for the 14th time in 15 years, outpacing the nation's inflation rate. Outlays have more than doubled since 1978, and have more than tripled since before the 1973-74 Arab oil embargo sent gasoline prices skyrocketing.

The latest report calculates such auto expenses as insurance, maintenance and repairs as well as purchase price and depreciation. However, it noted that some costs can vary widely from state to state.

All costs are based on typically equipped cars driven 10,000 miles a year for five years -- which is typical for new cars.

Typical compact car purchase prices last year rose nearly 7 percent to $11,155, up from $10,439 in 1986. The average price of an intermediate-sized car rose to $13,880 from $11,572 in 1986 -- and has more than quadrupled from 1972, when it cost an average $3,425, the study showed.

While compact cars are the most popular size car these days, subcompact cars accounted for the sharpest year-to-year gain in operating costs, up nearly 18 percent to $4,757 last year.

The smallest gain was among new full-sized cars, which rose only 5.4 percent. But as expected, they were the costliest to operate, rising to $6,637 a year, Hertz said.

Minivans, a popular alternative to cars, were not included in the study because the company does not have enough historical data on them.

Expenses among all categories rose from 1986 levels, the study showed. Average depreciation costs for compact cars, for instance, rose 6.9 percent in 1987 to $1,774 a year. Maintenance and repair costs rose 2.4 percent from 1986 to $464, while gasoline and other service station charges rose nearly 3 percent to $741.

Interest rate costs increased 3.5 percent after falling slightly last year due to cut-rate financing deals offered by carmakers, figures showed.

As always, Hertz stressed that keeping cars longer can save motorists substantial amounts of money. While a new compact car -- the most typical size -- would cost $6,250 annually if traded after one year or 10,000 miles, it would cost only $3,980 if run for 10 years at the same yearly mileage.

Hertz also said a late-model used car can cost as much as 40 percent less than a new one.