Wholesale vehicle prices climbed sequentially for the second straight month and posted a year-over-year gain for the first time in 2016.

But don’t take that to mean those supply-driven expectations for downward sloping used prices are suddenly over, Tom Webb warns in commentary accompanying the latest Manheim Used Vehicle Value Index.

“They do suggest, however, that dealers have continued to achieve efficiency gains that are allowing them to bid up auction prices even as gross margins narrow,” he said, referring to the two straight months the index has climbed sequentially.

“That’s encouraging to commercial consignors who have been expecting, and preparing for, greater weakness in wholesale pricing,” said Webb, Cox Automotive’s chief economist.

The May reading of Manheim’s index was at 124.5, which is up 0.6 percent year-over-year.

Pickups, whose prices were up 6.3 percent from May 2015, vans (up 1.5 percent) and luxury cars (0.6 percent) showed value gains.

Midsize cars and SUVs/CUVs were both down 0.3 percent. Compact cars showed the most contraction, as their prices fell 5.1 percent.

The latter found Webb posing this question in his comments: “Did compact car prices find a floor?”

On a mileage- and seasonally adjusted basis, their prices were up more than 2 percent month-over-month.

“If you’re optimistic, view it as a ‘dead cat bounce.’ Year-over-year, compact cars remained the weakest segment — and they too had a sizable number of off-lease units coming back,” Webb said. “So, yes, if a floor was found, that would be a good thing.”

Regarding Webb’s point on off-lease volume for compact cars, it has also led to these vehicles — along with midsize cars — grabbing the most share of the certified pre-owned market.

According to the Q1 Used Vehicle Market Report from Edmunds.com, 21.1 percent of CPO sales in Q1 were midsize cars and 20.6 percent were compacts.

The next closest was the compact crossover SUV, with a 13.6-percent share of Q1 CPO sales.

“Despite having little to negative year-over-year price growth, midsize and compact cars are the largest CPO segments,” Edmunds said in the report. “Leasing in these segments has become quite prevalent and has led to a healthy supply of vehicles that meet certification standards.”