GM’s domestic auto sales fell in early December.

The 12% decline from the like 1985 quarter contrasted with gains by Ford Motor and Chrysler. Industrywide U.S.-made car sales increased by 5.2% during the Dec. 1-10 period, compared to a year ago, the auto makers reported. Ford’s sales of domestic-made cars were up 33.5% over the year-ago period and Chrysler’s rose 24.7%. GM’s car sales were down 2.1% for the year to date, compared to the same period of 1985. The December period was GM’s sixth straight declining sales period in a slump marked by the absence of deep-discount financing incentives.