They had not been informed that the auto maker switched engines in the vehicles for ones made by its Chevrolet division.
G.M.'s Chevrolet division was hit especially hard, with sales down 34.3 percent from a year earlier.
The Chevrolet division is currently recovering from the economic downturn of 2007-2010.
In 1934, he joined General Motors, becoming chief design engineer of Chevrolet division in 1935.
The greatest strength was in the Chevrolet division, where sales spurted 41.1 percent in the month.
Ford sold the most trucks in its history, as did General Motors' important Chevrolet division.
Her father retired as the director of industrial engineering at the Chevrolet division of General Motors.
Yet G.M.'s Chevrolet division has had almost 400,000 fewer sales this year than last.
The Chevrolet division re-opened the plant in 1935 to build car and truck transmissions.
The car was first produced during 2010 and is manufactured by Chevrolet division of General Motors.
