Used compact vans and several categories of crossovers increased in value in wholesale sales, while luxury vehicles made up seven of the 10 lowest performing categories among 2013-2017 vehicles in May, according to Black Book.

Vehicles from those model years depreciated 0.3% in the month with cars falling 0.7% and truck-based vehicles essentially flat with a 0.1% decline. All vehicles fell 14.1% in value from a year ago. The month was an improvement over May of 2017, which saw a 1.2% decline from April of that year.

"After a strong spring, we are now beginning to see a higher depreciation pattern returning to many of the car and truck segments," said Anil Goyal, Executive Vice President, Operations at Black Book. "Unless demand driven by a strong economy continues to build, we expect the used vehicle market to begin seeing more depreciation as we get deeper into the summer months."

Fleet-category vehicles performed well, including compact vans, which increased 0.5% in May to $10.197. Full-size pickups increased 0.2% to $22,920. Small pickups increased 0.1% to $20,194.

Despite the slight dip in total vehicle values last month, eight segments saw positive changes in May, led by sporty cars (1.1%). Subcompact crossovers finished with the next highest change in valuation on the month (0.7%). This segment finished May with an average price of $10,698, a 13.8% decline from a year ago.

Luxury cars finished with the highest depreciation on the month and were down 1.6%. Vehicles in this segment finished with an average price of $18,215, a 10.8% decline from year-ago levels. Three other segments finished the month with a depreciation rate of 1.1% during May, including midsize luxury SUVs, prestige luxury cars, and near luxury cars.

Related: Cars Outpace Trucks, Vans in April Depreciation