SANTA MONICA, Calif. -

In what TrueCar has called a “sizeable speed bump” to the auto market’s rebound, analysts are expecting May to finish at what would be the softest seasonally adjusted annualized rate for new-vehicle sales so far in 2011 and close to a nine-year-low incentive level.

New-vehicle sales are expected to drop on a year-over-year and sequential basis during May, with used sales faring somewhat better, according to TrueCar.

Specifically, TrueCar is expecting new-vehicle sales (retail and fleet combined) for May will come in at 1.06 million, which marks a 3.7-percent year-over-year decrease and an 8.3-percent month-over-month decrease (unadjusted).

The resulting SAAR would be 11.85 million, off 1.33 million from the prior month’s pace.

On the used-vehicle front, TrueCar foresees May sales of 3.81 million units, which would be 3.4-percent stronger than April, but 8.9 percent softer than the year-ago period.

With regards to incentives, TrueCar anticipates that the automakers will have spent about $2,017 per unit on incentives during the month. This is 28.9-percent softer than the year-ago period and represents a month-over-month decline of 13.1 percent.

“Inventory constraints finally hit the Japanese automakers this month but the recovery in supply appears quicker than first anticipated,” explained Jesse Toprak, TrueCar’s vice president of industry trends and insights.

“Current inventory shortages and perceived inventory shortages led to the lowest incentive spending in nearly nine years and the lowest SAAR of the year,” he shared. “This is a sizeable speed bump on the road to recovery.”

As the new-vehicle market will likely soften from both the year-ago and month-ago periods, all but one of the top seven manufacturers are expected to be down from April.

Hyundai/Kia, with anticipated sales of 115,434 units, is the sole major OEM expected to improve from the previous month (up 6.1 percent), and is also one of three expected to show a year-over-year gain (up 43.4 percent).

Not only that, but it is projected to the be No. 3 automaker in terms of U.S. market share for May behind General Motors and Ford, respectively, and ahead of No. 5 Toyota, which usually perches itself near the top of the list.

Moving along, Chrysler (up 5.1 percent at 110,132 units sold) and GM (up 1.5 percent at 225,394 unit sold) were the other OEMs projected to see year-over-year growth.

Ford’s sales are projected to dip 1.9 percent from May 2010 and hit 188,280 units.

“High gas prices affected large truck sales dramatically hurting GM and Ford but because of their better balanced product portfolio due to their new fuel-efficient models, they were able to weather the storm with no major damage,” Toprak pointed out.

Toyota (down 32.8 percent at 109,416 sales), Nissan (down 20.8 percent at 66,371 sales) and Honda (down 20.7 percent at 92,889 units sold) are projected to see double-digit dips from May 2010.

Looking more at the projected May market share rankings for the seven major OEMs, these show GM in front (21.3 percent), followed by Ford (17.8 percent), which is the same positions they held a month ago. Hyundai (10.9 percent) comes in third after being sixth in April, while Toyota (10.3 percent) drops to fifth from the No. 3 spot.

Chrysler (10.4 percent) moves from fifth to fourth place, while Honda (8.8 percent) slides from No. 4 to No. 6. Nissan (6.3 percent) comes in at No. 7, same as April.

Sharing a bit more about incentives, all seven OEMs were down on both a year-over-year and month-over-month basis. Toyota’s incentives dipped the most for both comparisons (down 53.3 percent from April, 54.4 percent from May 2010).

The aggregate total for the industry’s incentive spending was $2.14 billion.