DETROIT — General Motors‘ U.S. light-vehicle sales fell 20 percent in the first quarter on declines at all four brands, but the automaker began to expand its fleet mix.

“Supply chain disruptions are not fully behind us, but we expect to continue outperforming 2021 production levels, especially in the second half of the year,” Steve Carlisle, president of GM North America, said in a statement Friday.

Buick, Cadillac and Chevrolet reported double-digit declines, while GMC’s deliveries fell 7.5 percent.

Full-size SUV sales were among the automaker’s bright spots last quarter. Deliveries of the Cadillac Escalade, Chevy Suburban and Tahoe and the GMC Yukon each grew more than 4 percent. The Yukon posted the biggest increase at 15 percent.

GM also accelerated fleet shipments last quarter, with fleet making up 24 percent of total sales. Fleet made up only 17 percent of GM’s total sales a year ago, but in the first quarter of 2020, before the pandemic significantly impacted the industry, fleet accounted for 28 percent of all GM deliveries.

Deliveries of EVs were slim during the latest quarter while the automaker continued to idle Chevy Bolt EV and EUV output due to a recall. Production of the Bolt is slated to resume April 4.

GMC sold 99 units of the GMC Hummer EV pickup last quarter, and Duncan Aldred, vice president of global Buick and GMC, has said GM plans to accelerate Hummer production to meet demand.

Brands: Buick, down 58%; Cadillac, down 24%; Chevrolet, down 20%; GMC, down 7.5%.

Notable nameplates: Buick Encore, down 58 %; Encore GX, down 71%; Envision, down 61%; Cadillac Escalade, up 6.7%; XT5, down 43%; CT4, down 28%; Chevrolet Suburban, up 11%; Corvette, up 33%; Silverado heavy-duty, up 11%; Silverado light-duty, down 11%; Blazer, down 2.4%; Trailblazer, down 66%; GMC Terrain, up 47%; Sierra heavy-duty, up 12%; Sierra light-duty, down 19%.

Incentives: $1,965 per vehicle, down 58% from a year earlier, TrueCar says.

Average transaction price: $50,717, up 18% from a year earlier, according to TrueCar.

Fleet mix: 24%. The first three months of the year marked GM’s best commercial sales quarter in nearly three years. Deliveries of commercial full-size pickups rose 5%, compact SUV sales more than doubled, and midsize pickup sales rose 23%.

Total fleet sales rose 10% from a year earlier. Commercial deliveries increased 14%, and government deliveries increased 18%. Chevy Tahoe sales to government customers increased 243%, GM said.

Inventory: 273,760 vehicles at the end of the first quarter, including in-transit units. That tally compares with 334,628 vehicles a year ago and 199,662 units at the end of the fourth quarter. GM expects relatively low stock levels throughout the year due to high customer demand.

Quote: “Ordinarily, a U.S. economy this strong would translate into light vehicle sales in the 17-million range,” GM Chief Economist Elaine Buckberg said. “Improvements in the supply chain should lift auto sales as the year progresses, despite headwinds from higher inflation and fuel prices.”

Did you know? In the first quarter, GM’s combined market share of Chevy Silverado and GMC Sierra heavy-duty pickups reached its highest point in more than a decade. The pickups held 41.5% of the market last quarter, up 10 percentage points from a year earlier, according to GM, citing J.D. Power PIN data. GM last year expanded production of heavy-duty pickups at Oshawa Assembly in Ontario.