U.S. auto makers yesterday reported a 0.8 percent gain in sales for the first 10 days of June, just topping strong year-ago levels despite lower showings by General Motors Corp. and Ford Motor Co.

The seven companies, GM, Ford, Chrysler Corp., Honda Motor Corp., American Motors Corp., Volkswagen of America and Nissan Motor Manufacturing U.S.A., reported combined sales of 218,247 cars in the United States during the period. This compares with 216,565 units sold in the year-ago period.

The annual rate for the industry during the period was 8.6 million cars, the same as in the year-ago period. So far in 1986, the companies have sold 3.62 million cars, down 6 percent from the 3.85 million units sold in the comparable 1985 period.

For the period, GM's sales were off 0.5 percent, while Ford posted a 5.2 percent decline. Chrysler reported a 15.7 percent gain.

Among the smaller companies, AMC's sales were off 38.6 percent, sales of Honda's U.S.-built models were up 169.7 percent from a year ago because of constricted supplies then, and sales of Volkswagen's domestic-made models were up 202.4 percent because of low availability last year.