General Motors says its June U.S. Sales for core brands in June were up 36%.
Analysts expect most automakers, led by GM, to show double-digit percentage gains in sales from the depressed sales results of a year earlier. That would represent the eighth consecutive month of year-on-year gains.
Industry tracking firm Edmunds.com sees GM sales up 17% in June from a year earlier, while projecting gains of 33% for Chrysler and 17% for Ford Motor Co (F).
Toyota (TM), tarnished by a series of safety recalls earlier this year, lagged rivals even after it extended sales incentives for a fourth consecutive month to win back consumers, Edmunds said.
The forecasting firm expects Toyota to post gains of 9% in June U.S. sales, less than gains of 10% and 25% it sees for Honda and Nissan, respectively.
Overall, incentives in June held flat from May but rose 6% from a year ago led by Toyota, industry tracking firm Truecar.com said. Toyota spent 33% more on discounts per vehicle in June than a year ago, sharply above the industry's average of $2,870 per vehicle.
"With the recovery not progressing as expected, it's gut-check time for the automotive industry," Schuster said.
"The industry's (pricing) discipline will be put to the test even more in the coming months if a more pronounced recovery doesn't get under way."
One key measure for the industry will be retail sales of cars, trucks, SUVs and crossovers. Sales gains in recent months, especially for Detroit automakers, have been boosted by sales of less-profitable vehicles to fleet operators, including car rental agencies.
Most automakers do not break out how many of their sales went to consumers and how many to fleet operators.
In one indicator of underlying consumer demand, AutoNation Inc, the leading auto dealership chain, will release its own sales figures Friday.
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