New car sales growth in Canada faces an uncertain outlook over the next few months, a widely-watched automotive analyst suggested Tuesday.

After a strong first three months in 2012, DesRosiers Automotive Consultants said in a report, data released by Statistics Canada yesterday suggests “a distinct softening during the spring and summer months.”

The analysis came as the Canadian Auto Workers union extended its strike deadline from midnight in order to try to reach similar tentative collective agreements with General Motors and Chrysler as it made with Ford on Monday.

First half new car sales of $42.5 billion still beat the same period in 2011 by 8.2 per cent, DesRosiers said, and topped anything in corresponding month in the last five years.

But after averaging 11 per cent in the first quarter, sales growth fell by half in the second quarter, to average 5.5 per cent.

DesRosiers noted the same trend among dealers of used vehicles, recreation vehicles and auto parts, where average increases of 7.6 per cent in the first three months slowed to 2.9 per cent in the second quarter, but still surpassed $10 billion, an improvement on the same period in 2011.

Gasoline station sales growth also declined in the second quarter to an average increase of 1.6 per cent from the same period a year earlier, compared with five per cent between January and March.