Ford Motor Co. and Fiat Chrysler Automobiles NV reported the biggest declines, and automakers’ U.S. sales trailed analysts’ estimates as heavy incentive spending failed to keep struggling sedan and compact models from plunging.

Deliveries slumped 7.2% at Ford and 4.6% at Fiat Chrysler last month. General Motors Co. sales climbed 1.6%, a smaller gain than analysts projected, while Honda Motor Co. reported a surprise drop.

The early results cast doubt on estimates that industrywide U.S. auto sales would rise in March compared with 2016’s weakest month, when results were depressed by the early Easter holiday. Automakers are using heavy discounts to try to trim inventory that’s swelled to the highest level in more than a decade.

“Sales are under forecast and there were a lot of incentives during the month,” Michelle Krebs, an analyst with Autotrader.com, said by phone. “Before long, we will see more production cuts.”

GM sees the industry’s annualized sales pace, adjusted for seasonal trends, accelerating to 17 million for the month, trailing analysts’ estimates for a rate of 17.2 million. The rate was 16.7 million a year earlier.

Deliveries of GM’s Chevrolet Malibu and Ford’s Fusion family cars each plunged by more than 35% last month. GM shares fell 3.7% to $34.06 as of 10:12 a.m. EDT. Ford was down 2.9% to $11.30.

“Many automakers are looking for signs of market stability as consumers continue to head toward trucks and SUVs,” Jeff Conrad, senior vice president of Honda’s U.S. sales unit, said in a statement.

Nissan Motor Co. sales rose 3.2%, beating analysts’ estimates for a 2.8% gain. Rogue crossover deliveries surged 43% in March, as the model continues to outsell the longtime leader within the segment, Honda’s CR-V.

By Jamie Butters and David Welch, with assistance from John Lippert.