Interest rates keep inching down

There's finally good news for American consumers:

* New auto loan interest rates were cut by a full 3 percentage points - to 14 1/2 percent - on Monday at the Bank of New York.

* Some mortgages in the Boston market have dipped into the 13-percent range.

And more good news could lie just ahead:

* Influential economist Henry Kaufman forecast more cuts in interest rates Tuesday.

* Speculation is growing that the prime rate could drop as low as 10 percent soon.

But it may be a while before all the good news is felt by consumers:

Bankers informally surveyed by the Monitor across the United States say that it could be quite a while before the average American sees a substantial drop in consumer interest rates from this point.

Bankers checked by the Monitor concede that interest rates will inevitably fall. But they add that consumers won't see a rapid decrease in rates available to them. Instead, impressions gathered in the Monitor survey suggest that lenders will be testing the still-troubled economic water before plunging wholeheartedly back to lower interest rates.

A steady, but slow, decline in mortgage rates and some erratic drops in auto loans - especially in New York where at least two banks have dropped new auto loan interest rates from 17.5 percent to 14.5 percent in the past week - was evident from the Monitor survey.

But one banking analyst expressed skepticism about the New York-area auto loan rates and at just how much real interest rate cutting has occurred, or will occur immediately in any area.

''It looks good on paper,'' said Harold Levine, senior banking analyst with E. F. Hutton. ''But you know they're serious when they lower revolving credit rates - that's a bigger slice of the portfolio, and where the rates [and profits ] are the highest.'' (The interest rate on credit card accounts has been untouched at all but one of the banks surveyed by the Monitor, and many of those rates have remained at 19 percent-plus for at least a year.)

Other financial experts continue to point out that a number of institutions, especially those in California and thrift institutions that are more heavily dependent on consumer business than Eastern banks, may be slower to reduce the cost of loans. They are locked into commitments on high interest, long-term deposit accounts. Further, they add, lenders will be reluctant to take on fixed rate mortgages after being burned on them during the current recession when they had to pay high rates of interest to depositors while waiting for long-term fixed interest loans to come due.

Consumers can also expect even slower decreases in interest rates at savings and loan institutions, which are more directly tied to long-term mortgages, many of which are still only bringing in 8 percent a year. The National Savings and Loan League's Economic Advisory Board has forecast that the average new S&L mortgage offered by the end of the year will still have interest as high as 14.5 percent, and 13.5 percent by the end of 1983.

Mortgage rates have been steadily dropping since March, according to Federal Home Loan Bank Board data, which indicate the sharpest monthly drop in the national average mortgage interest rate between August and September when interest charged moved from 17.01 percent to 16.23 percent (on 25-year, fixed interest mortgages). Variable rate mortgages were reported in some areas as low as 13 percent and federally guaranteed loan rates are as low as 12.5 percent.

Indications are that Americans have eagerly anticipated the downturn of consumer interest rates that follows a dip in the prime rate. In Boston, a real estate industry spokesman reported that home showings doubled over the weekend following the move by major banks to drop their prime rates. A new variable rate mortgage offered by Chemical Bank in New York brought 400 inquiries last week alone.

Each point of interest lopped off the cost of a mortgage, said Richard DeWolfe, president of the Greater Boston Real Estate Board, increases the buying power of an individual by 7 percent.