Year-over-year sales of passenger cars, pickup trucks, vans and other light-duty vehicles to commercial fleets fell 2.1 percent to 52,445 units in June, according to Automotive Fleet data.

The decline in fleet sales was the first in 2015, as fleet sales have slowed in recent months from nine manufacturers who provide data for the monthly report.

General Motors increased sales to commercial fleets by 4 percent, including an 18-percent increase in pickup sales, GM announced separately. Year to date, GM has increased commercial deliveries by 20 percent.

Trucks, vans, and SUVs made up the bulk of the sales with 45,059 units, but the category fell 5.8 percent from a year ago. Sales of passenger cars increased 29.8 percent to 7,386 units.

Ford reported its strongest month for van sales since 1999 with 21,419 units sold for a 31 percent increase from a year ago, when its full-size Transit began to enter the market as an E-Series replacement. Since its debut, Ford has sold 78,091 Transit vans of the more than 100,000 it has built in Kansas City, according to a spokeswoman.

Fleet sales remain higher for the first half of the year with a 3.4 percent increase to 325,870 units compared to the same period in 2014. Sales of trucks, vans, and SUVs have increased 2.1 percent to 269,941, while sales of passenger cars have increased 10.1 percent to 55,929.