Not only is the continuing month-long strike by UAW workers of American Axle, a major parts company in the U.S., contributing to the idling of its Oshawa truck assembly plant and threatening the same for its local car plant but it also saw a decrease of 16.4 per cent in sales over the same month last year.

Overall, GM Canada's car sales were down 8.9 per cent while truck sales were down a considerable 21.9 per cent or more than 4,500 units. GM dealers delivered 30,208 units in March.

But GM spokeswoman Patty Faith noted that year-to-date GM Canada sales are up marginally at 1.5 per cent.

"GM is holding its own in Canada; we had a strong first quarter," said Ms. Faith. "(March) tends to be a softer selling period. The spring selling season is usually more robust."

She was unable to predict how much time remains before the car plant runs out of its stock of Axle parts and is forced to shut down temporarily. The regular weekday shift plus an added overtime shift Saturdays continues to run.

"We will be monitoring the situation," Ms. Faith said. There is no word on whether talks have resumed between Michigan-based American Axle and its workers' union the United Auto Workers.

The strike has also impacted hundreds of local auto sector workers at GM and feeder plants like Automodular in Whitby and Lear (Ajax).

So far the shutdown of the truck plant has not had a major impact on dealership inventory and sales although some dealers may be running low on certain makes and models depending on their sales, said Ms. Faith.

The overall first quarter sales increase were driven by a strong 17.2 per cent quarterly increase in car sales, especially fuel-efficient vehicles.

Sales of the fuel efficient Pontiac Wave and Chevrolet Aveo rose a combined 77.6 per cent, compact cars posted a 9.5 per cent increase driven by the double-digit gains for the Chevrolet Cobalt and Pontiac G5 and mid-size cars were up a full 79.6 per cent on the strength of a 125 per cent increase for the all-new Chevrolet Malibu.

"We are very pleased with those results," said Ms. Faith. "Higher fuel prices are impacting purchasing decisions."