Limited incentive programs and a late November cold snap caused a slump in new car buying activity as car sales for the month dropped 14.1 percent from year-ago levels, the auto industry reported yesterday.

The seven companies, General Motors Corp., Ford Motor Co., Chrysler Corp., Honda Motor Corp., American Motors Corp., Volkswagen of America and Nissan Motor Manufacturing U.S.A. reported combined sales of 515,802 cars in the United States during the latest month. This compares with 600,692 units sold in November 1984. The daily selling rate of 20,632 cars compares with 24,028 for the same period last year.

The annual rate for the industry during the period was 6 million cars, compared with 7.1 million last year. So far in 1985, the firms have sold 7.64 million cars, up 3.5 percent from the almost 7.4 million units sold in the comparable 1984 period.

For the 10-day period of Nov. 21-30, U.S. auto makers sold 184,506 cars, a decline of 1.2 percent from the 186,721 units sold in the year-ago period. The daily selling rate of 23,063 cars compares with 23,340 for the same period last year. The annual rate for the industry during the period was 6.4 million cars, compared with 6.3 million last year.