CARY, N.C. -

Though it is currently a bit softer than year-ago figures, overall auction volume should exceed 2017 levels “soon,” according to the latest Guidelines report from J.D. Power Valuation Services.

The report released this week is updated through the year’s first five months. It found that overall auction volume is down 0.7 percent.

However, that could change.

“Year over-year volume continues to grow with each passing month, and as a result there should be a transition soon where there is more overall auction volume compared to 2017,” J.D. Power analysts said in the report.

Looking at late-model units, specifically, they had a 12-percent month-over-month gain in volume during May. Late-model volume climbed 2.6 percent year-over-year last month.

Separately, J.D. Power Valuation Services looked at used-car supply trends in detail as part of its spring Perspective report.

In that report, analysts project a 4.1-percent year-over-year hike in the total supply of used cars up to 5 years old in 2018. There is likely to be a 14.2-percent increase in the crop of off-lease units, in particular, which remain the key catalyst to supply growth.

Retail purchase supply is likely to grow 2.6 percent, with rental and commercial volume falling about 3 percent — which would be the first “material decline” for that crowd in four years, according to J.D. Power.

All this follows last year’s 7-percent growth in supply of used cars up to 5 years. Off-lease volume was up 13.5 percent in 2017.

In its 2018 Used Car Market Report & Outlook released earlier this year, Cox Automotive said it expects another year of 10 million wholesale vehicles at traditional, brick-and-mortar auto auctions in 2018.

The report’s section on wholesale volumes and pricing was written by Zohaib Rahim, manager of economic industry insights at Cox Automotive .

In that section, Rahim said wholesale volumes at physical auctions should remain at this “near-record” height referenced above. In 2017, the tally was close to 10 million, according to an estimate of member auction sales by the National Auto Auction Association cited in the Cox report.