Domestic-brand dealers increased their April certified pre-owned sales by more than 15 percent, pushing their year-to-date total above 300,000 units, according to Autodata Corp.

The Big 3 sold a collective 78,864 CPO units for the month, beating April 2014 figures by 15.5 percent, Autodata noted.

Through four months, domestic certified sales reached 312,763 units for an 18.3-percent hike.

Over at Ford, its brands combined to move 24,777 certified vehicles in April, which marked a 13.1-percent increase. Sales through four months were at 93,431 units (up 8.9 percent year-over-year).

Certified sales for the Buick, Chevrolet, GMC, Pontiac and Saturn brands at General Motors reached 36,666 units for the month (up 10.9-percent) with yearly sales hitting 152,599 units (up 21.5 percent), Autodata indicated.

Cadillac dealers moved 2,402 CPO vehicles (up 28.3 percent) in April, with year-to-date sales at 8,666 units (up 29.2 percent).

There was a combined 15,019 Chrysler, Dodge, Jeep and Ram CPO sales in April (up 31.7 percent). Year-to-date sales were at 58,067 units (up 25.6 percent).

CPO sales for Fiat (which are not included in the aforementioned totals) were at 81 units in April (up 170 percent) and 272 for the year (up 112.5 percent).