A strong month for new-car sales evidently will take a toll on the August used-vehicle sales performance if the projections from Edmunds.com  come to fruition.

The site expects this month’s used sales level to soften slightly from July’s figure, estimating the total amount of transactions at franchised and independent stores as well as private-party deals will total 3.1 million. That amount left Edmunds’ used seasonally adjusted annual rate for August at 36.9 million.

The site indicated there were 3.2 million used sales in July, resulting in a SAAR level of 36.3 million.

During a conference call on Thursday that mainly discussed how new-vehicle sales might land this month, Edmunds.com senior analyst Jessica Caldwell made the connection between strengthening new-car sales and used-vehicle sales that might be off a bit.

“Used sales have obviously been hot over the last few years,” Caldwell began. “Clearly the used market is not as clear, cut and dry as the new market because you have private-party sales and independents. 

“It’s very seasonal. There’s definitely ups and downs,” she continued. “In terms of the softening, whenever there is more opportunity on the new-car side, whether it’s incentives or longer loan rates, there is more flexibility on the new side, and that can hurt used-car sales.”

Edmunds thinks there are going to be 1,287,603 new models sold in August for an estimated SAAR this month of 14.5 million light vehicles. 

If the numbers hold, Caldwell indicated August will be the second-best month of the year in terms of SAAR and the third-best month in terms of unit sales.

“Sales showed signs of flattening out in the first couple months of summer, so August’s sales figures will come as a nice surprise for everyone in the auto industry,” Caldwell highlighted.

“Automakers and dealers have been very creative in packaging hidden incentives in recent weeks, and when you combine that with the sell-down of popular 2012 model year vehicles, there have been some nice deals available to car buyers,” she continued.

Going back to the used-car side, Caldwell pointed out the projected downturn for August likely won’t develop into an extended trend.

“Used sales have been so strong over the past few years that it’s going to slow down at some point, but that’s not necessarily a trend. I think it can bounce back to where it was,” Caldwell stated.

TrueCar’s Used-Car Projections

Earlier this week, TrueCar called for 3.99 million used sales this month, which would be a 4.7-percent increase from a year ago.

“It’s mostly an inventory-driven increase,” explained Jesse Toprak, the company’s vice president of market intelligence.

In essence, the increase in new-car sales volumes in recent years has now led to “slightly” greater availability of used units aged three years or newer, Toprak said.  There are simply more of these cars out there.

Also driving the year-over-year increase has been sales of the $10,000-and-under crop of used units, as Toprak noted, “That business remains strong.”

Granted, the nearly 4 million used sales expected industry-wide in August would be down 13.3 percent from July, TrueCar noted. However, Toprak attributes this mostly to “seasonality.”