CHICAGO - The US auto industry struggled to maintain past sales momentum in August, with General Motors, Ford and Nissan selling fewer vehicles as less discounting kept customers from showrooms.

But the North American unit of Fiat Chrysler reported a three percent sales increase buoyed by its popular Jeep sports utility vehicles.

General Motors, the biggest US automaker, reported an eight percent sales decline compared to August 2015. Ford reported a five percent drop, and Nissan a 6.5 percent drop — a departure from high sales numbers in previous months.

Automakers offered a positive take on the numbers, saying the average amount customers paid for a car or truck — the average transaction price or ATP — had increased. “Our retail strength is reflected in our record ATPs in August, which were up more than $1,600 from last month and nearly $5,800 above the industry average, while our incentive spending was below the industry average and well below our domestic competitors,” Kurt McNeil, head of US sales for GM, said in a statement.

The average vehicle price had already gone up 2.5 percent in July, compared to a year ago, to $34,264, according to Kelly Blue Book. KBB analyst Tim Fleming warned last month that such price increases could drive customers to used cars, “which could mark a big departure from the new-car sales growth the industry has seen during the past five years.”

There are already indications that the brakes are being applied to the industry’s sales boom, which has been fueled by low gas prices and interest rates and an improving job market. In July, the seasonally adjusted annual rate of sales ticked up to 17.88 million units, compared with 17.59 million in July 2015, according to Autodata. But sales declines among the largest automakers suggested that if overall sales were rising, they were doing so more slowly.

“It’s too close to call whether 2016 will surpass 2015’s record-setting sales,” senior analyst Michelle Krebs of Autotrader told AFP.

“It depends what happens in these last months of the year and what automakers to do spur sales in the way of incentives and promotions.”

Even if 2016 proves to be the end of sales increases, Krebs predicted that the industry would still sell about 17 million vehicles a year — a very high number — for two more years.