LAWRENCEVILLE, Ga. -

Temperatures are rising nationwide with the first official day of summer coming soon, but prices on certain cars and trucks keep dropping noticeably as auctions and dealers enter the summer months.

However this week’s Black Book Market Insights report indicated a few segments, such as sporty cars and compact vans, have remained strong during the last few weeks.

“The used-vehicle prices are dropping faster as we enter the summer lull with increasing no-sales in the auction lanes,” said Anil Goyal, executive vice president of operations at Black Book.

Volume-weighted, editors determined overall car segment values decreased by 0.24 percent last week. In comparison, the values had softened an average of 0.16 percent per week during the previous four weeks.

Within cars last week, Black Book determined midsize cars declined the most (0.55 percent or $51), while sporty cars increased the most (0.38 percent or $59).

Volume-weighted, editors found overall truck segment values (including pickups, SUVs and vans) dipped by 0.17 percent last week. In comparison, the values had decreased on average by 0.07 percent per week during the previous four weeks.

Among trucks last week, sub-compact luxury crossovers decreased the most (0.60 percent or $103) while compact vans increased the most (0.82 percent or $74).

As Goyal referenced, lane activity is starting to tail off a bit as recounted by Black Book’s representatives stationed at about 60 sales each week.

“Consignment is down as is the dealer attendance and participation at the auction,” the observer in Michigan said. “Thankfully, the Internet buyers continue to be heavily involved in purchasing the auction inventory.”

A similar scene unfolded in Pennsylvania where the Black Book personnel noted, “Dealers are hesitant about overstocking as we move into the vacation season. There were many no-sales in today’s auction.”

And the trend wasn’t confined to auctions west of the Mississippi as Black Book’s lane watcher in California added, “We had a good mix of inventory to choose from today, but the result was still a lot of no-sales.”

The other two anecdotes Black Book shared from its auction watchers reflected other trends often seen this year, including:

— From Indiana: “Retail on the used-car side is good. Nice vehicles remain scarce, especially regarding the truck market.”

— From Washington: “We had a low volume of inventory, and a lot of those were high mileage vehicles resulting in an average or below sale.”