Used-vehicle sales are expected to remain relatively static on a year-over-year basis for September, but fall double-digits from August, according to TrueCar.com.

On the new-vehicle side of the market, though, sales look to be down 5 percent month-over-month (unadjusted). However, this decline is much slower than the usual August-to-September dip, something that TrueCar vice president of industry trends and insight Jesse Toprak said may be a positive indicator for the market.

Not only that, new-vehicle sales will likely move ahead close to 28 percent from September 2009.

“Historically, the average drop is 10 percent from August to September, so the lack of a double-digit drop this month could be a sign of relative strengthening in the market,” Toprak noted. “But consumers continue to seek value-oriented brands such as Hyundai or Kia due to a lack of clarity in the economy.”

Specifically, TrueCar is projecting used sales of about 3.29 million units, which would be 16.6 percent softer than the total for August. This would be a 0.6-percent year-over-year gain.

The resulting new-to-used ratio would be 1:3.45.

For new-vehicle sales (including fleet), there will likely be 951,382 units sold. The resulting seasonally adjusted sales rate would be 11.66 million vehicles, as compared with 11.47 million the prior month.

Breaking it down, TrueCar said Hyundai/Kia is expected to show the biggest year-over-year increase in new-vehicle sales (59.5 percent), as it is predicted to move 84,723 units.

Of the top seven OEMs, General Motors is likely to sell the most vehicles at 170,905 units, a 10.4-percent year-over-year uptick.

All seven manufacturers are predicted to show year-over-year gains. Only one — Toyota — is expected to remain steady from August, while the others are expected to decline.