Two of the Big 3 automakers posted best-ever certified pre-owned sales figures last month, and collectively, domestic brands have moved nearly 400,000 CPO units this year.

That’s the latest from Autodata Corp., which has released its monthly recap of industry-wide certified sales.

The industry as a whole had its best CPO month ever. As for the Big 3, they combined to sell 81,686 CPO units in May, which beat year-ago figures by nearly 18 percent, according to Autodata.

Through five months, they moved 394,449 certified vehicles for an 18.2-percent increase.

Breaking all-time CPO records, Autodata said, were Ford Motor Co. and Fiat Chrysler Automobiles.

The brands at Ford combined to move 26,097 certified vehicles in May, which marked an 11.7-percent year-over-year increase.

Through five months, they’ve sold 119,528 CPO vehicles for a 9.5-percent upswing.

Excluding Fiat results, the Chrysler, Dodge, Jeep and Ram brands at FCA moved 16,579 certified units in May (up 29 percent) and have sold 74,646 CPO vehicles in five months (up 26.3 percent).

With Fiat sales included, FCA moved 16,661 CPO units for the month, a 29.2-percent increase. The five-month total is at 75,000 units, up 26.6 percent from last year’s pace.

(The aforementioned Big 3 total does not include Fiat figures).

At General Motors, there were 36,916 CPO sales of Buick, Chevrolet, GMC, Pontiac and Saturn vehicles in May, which beat year-ago figures by 18.2 percent. Year-to-date sales are at 189,515 units (up 20.8 percent).