Slow sales of passenger cars are prompting General Motors to change its production plans at a big assembly plant.

GM won't comment on specific production plans, but did say it intends to keep current production in line with demand.

The Wall Street Journal is reporting this morning that GM will shut down the plant in mid-November for six weeks.

The Hamtramck plant makes four poorly performing sedan models, including the Buick LaCrosse, sales of which are down 21.5 per cent year to date, and the Chevrolet Impala, which is down 31.8 per cent.

In the first nine months of this year, the Detroit-Hamtramck plant produced 75,361 vehicles, a 43 percent decrease from the 132,086 it built in the same period in 2016, according to the Automotive News Data Center.

Meanwhile, Reuters reported Wednesday that GM has warned a striking Canadian labor union that if it doesn't call off a monthlong walkout, the automaker will shift production of the top-selling Chevrolet Equinox SUV to Mexico. The planned reduction will reportedly cost 200 jobs at the facility.

In the first nine months of 2017, GM sold 15,634 LaCrosse models, a 21 percent drop from previous year.

GM, like Ford and other automakers, is realigning production as consumer demand shifts markedly from passenger cars to SUVs and trucks.

Production cuts slice into revenue, but could also helps automakers avoid deeper price cuts on vehicles they can sell.

Earlier this year, GM eliminated the plant's second shift, saying it was laying off around 1,200 workers.

A GM spokesman said there are no plans to reinstate any of those shifts at this time.