Mid-January sales of domestic cars soared to the highest level in 13 years and beat last year's robust showing by 18.1 percent, the seven major auto makers reported yesterday.

The companies reported sales of 199,246 cars in the Jan. 11-20 period compared with 168,668 last year.

The sales rate for the period came to an average 24,906 deliveries a day in eight official selling days, the best since 27,913 a day in 1973. The performance was attributed largely to incentive programs such as cut-rate financing and rebates that expire across the industry on Feb. 22.

However, Ford Motor Co. maintained its market share at nearly 25 percent and posted the biggest year-to-year increase in sales -- 21 percent -- while offering the incentives only on its subcompact cars. General Motors Corp. showed a sales increase over the 1985 period of 18.2 percent and had 58.7 percent of the market for domestic makes. Chrysler Corp. reported a 13.2 percent increase in sales and a 12.3 percent share.

The seasonally adjusted annual rate of sales for the Jan. 11-20 period was 9.9 million, well above auto makers' expectations for the year and far above the 8.4 million recorded in the period a year ago. Actual sales for 1985 were 8.2 million, and the auto companies are predicting a slight decrease from that in 1986.