General Motors says weaker fleet deliveries and dog-eat-dog competition in the luxury-vehicle market put the brakes on its U.S. sales in April, but it appears the auto maker will claw back some of the market share it lost in March.

“As you dig into the numbers, you will see clear evidence we are still seeing good, broad-based sales performance across our portfolio,” says GM Vice President and chief sales analyst Don Johnson.

GM delivered 213,387 light cars and trucks last month, up 3.2% on a daily selling basis, compared with 232,538 year-ago when the industry saw three extra selling days, according to WardsAuto data.

Some competitors posted a blistering sales month, such as Chrysler’s 35.4% surge and Toyota’s 25.5% spike.

But GM still managed to regain some share lost in March, when the auto maker’s piece of the U.S. market fell to an all-time low of 16.5%. GM’s share was tracking at about 18.0% for the month earlier today, before all auto makers could complete reporting April sales.

GM blames much of its poor year-over-year performance on fewer fleet sales, as deliveries to rental-car companies, commercial customers and government agencies fell 25%.

Johnson says GM sold 19,000 fewer units to fleet in April compared with year-ago, and half of those were vehicles the auto maker no longer makes. He expects fleet deliveries to account for about 25% of GM’s sales mix this year, as originally forecast.

GM’s Cadillac and Buick divisions did the auto maker no favors in the month.

Cadillac deliveries fell 15.6% on a DSR basis. GM says it does not want to match the incentives key competitors are using.

Luxury sales overall have been trending slightly upward this year. However, Cadillac no longer sells two models, the DTS and STS large cars, a hole in its lineup the new-for-’13 XTS should plug.

“The other luxury makes are being very aggressive in the marketplace,” says Curt McNeil, vice president-sales at Cadillac. “Their incentive spends are up anywhere from 10% to 50%, so they are out spending money.”

Buick sales slipped 5.6% in April, with fleet deliveries plunging 77% as the auto maker seeks to improve the residual values of the brand’s products by focusing more on the retail market.

Buick also recently lost the Lucerne large car. But LaCrosse sales were off 9.5% and Regal deliveries slid 29.1%. The new-for-’12 Verano small car posted its best sales month since launch late last year with 2,989 units, and 50% of its buyers are coming from non-GM brands.

GM’s volume Chevrolet brand saw sales inch up 3.0% year-over-year in April. Passenger-car sales at the division fell 8%, marked by an 18.6% decline in demand for the Cruze compact car.

Deliveries of the closely watched Volt extended-range electric vehicle totaled 1,462 units, down 36% from March but the car’s third-best month since its launch.

GM raises its industry sales forecast today to a seasonally adjusted annual rate of between 14 million and 14.5 million units, up from 13.5 million to 14 million previously.

The auto maker cites better-than-expected industry sales in the first quarter, as well as expectations the U.S. economy will continue to grow and the manufacturing and retail sectors will add jobs and keep demand for new cars and trucks strong.