Retail sales fell 0.4 percent in December following an upward revised 2.6 percent gain in November, the Commerce Department reported yesterday.

The December drop, due entirely to a decline in auto sales from high November levels as special low-interest-rate financing programs wound down, was less than most analysts had expected. At a seasonally adjusted level of $92.3 billion, December sales were 2.2 percent higher than in October.

The encouraging news on retail sales contrasted with the results released yesterday of a Commerce survey of business intentions to invest this year in new plants and equipment.

The survey showed non-farm businesses plan to invest $315.7 billion this year, 5.2 percent less than in 1982 after adjustment for about a 4 percent rate of inflation for capital goods prices.

Economic forecasters have been predicting that a drop in business investment during 1983 would be a major factor in keeping the anticipated economic recovery running in low gear. The department also said that spending for new plants and equipment was $320 billion last year, down slightly from $321.5 billion in 1981.

At the same time, however, capital goods prices climbed an estimated 4.8 percent, so that the real level of investment fell at roughly that rate.

The largest declines planned for 1983 are in several of the basic industries hardest hit by the recession. Primary metals producers, for instance, expect to spend 18.5 percent less in actual dollars and therefore still less after accounting for inflation.

The petroleum industry, confronting a worldwide over-supply of oil, will cut investment by 10.8 percent, the survey indicated.

About the only industry expecting an increase in real terms for 1983 is the rubber industry, which will invest 13.4 percent more.

The report on retail sales showed that sales other than in the automotive group rose 0.5 percent in December following a revised 0.4 percent gain in November. Furniture, home furnishings and equipment stores reported increases of 2.2 percent for December after a strong 1.9 percent increase the month before. The report, which is based on a small sample of stores and is subject to revision, left retail sales 6.6 percent higher than in December, 1981.