According to The Detroit News, capacity utilization at GM plants was the main factor to decide which facilities to cut, by picking those who operate below 80% of their full capacity, the minimum percentage required to break-even in financial terms.
The News states that GM operates eight of its 12 assembly plants in the U.S. at 80% or less this year, citing data from LMC Automotive. In contrast, only three of Ford's nine U.S. assembly plants were running below that level in 2018 and two of Fiat Chrysler's six plants.
Meanwhile, the GM San Luis Potosi plant, that produces the automaker’s second-best selling vehicle, the Equinox, has run at 91% capacity utilization this year and the facility in Silao, Guanajuato is running at 145% by running extra shifts.
You can read the whole report here.