Sales at Orange County auto dealers increased 9% in May to 12,417 vehicles, according to Newport Beach-based Orange County Automobile Dealers Association.

The figures are based on new retail car and light truck registrations in OC.

Japan-based brands accounted for nearly half of last month’s sales here, at 6,184, up 4% from a year earlier.

Toyota Motor Corp. led all automakers locally despite a 12% drop to 2,293 vehicles sold in May.

Mazda Motor Corp., which has its North American operations in Irvine, had a 45% increase in vehicles sold here in May, for a total of 378.

Cypress-based Mitsubishi Motors North American Inc. had 83 sales locally, down 2% from a year earlier.

The locally based U.S. operations of two brands from South Korea had mixed sales last month.

Costa Mesa-based Hyundai Motor America Inc. sold 716 vehicles here, down 5% year over year.

Kia Motors America Inc. in Irvine sold 584 vehicles from OC dealers, up 22% from a year ago.

OC’s auto dealers have sold 65,206 vehicles during the first five months of this year, up 14% from the same period last year.