SANTA MONICA, Calif. — This month's new vehicle sales (including fleet sales) are expected to be around 1.17 million units, nearly a six percent decrease from August 2008 but up nearly 18 percent from July 2009, according to Edmunds.com.

Edmunds.com analysts predict that August’s seasonally adjusted annualized rate (SAAR) could be just over 13 million, this year’s highest by far. However, a week-by-week analysis reveals that this summer has been the industry’s most volatile period in history, due to the government’s Car Allowance Rebate System (CARS), also known as Cash for Clunkers.

“Cash for Clunkers sent the sales rate on a wild roller coaster ride,” said Edmunds.com senior analyst Jessica Caldwell. “The SAAR surpassed 19 million in late July, bounced around in the 15 million range early in August and has fallen to around eight million currently. Ending August on such a low note does not bode well for September.”

Edmunds.com analysts note that the unusual inventory shortage faced by many dealerships could mean that deals are stuck in the pipeline and, when accounted for, will move the numbers significantly.

August 2009 had 26 selling days, one less than last August 2008. (The chart below sets forth other unadjusted and adjusted comparisons.)

“Hyundai and Ford were the biggest winners in the Cash for Clunkers contest, experiencing significant growth in August sales compared with a year ago,” said Edmunds.com senior analyst Michelle Krebs, whose analysis of Edmunds.com’s August sales forecast can be found on AutoObserver.com. “This is likely to be a record month for Hyundai, beating their prior sales record by a mile — maybe as much as 40 percent.”

“In contrast, some automakers couldn’t really make Cash for Clunkers work for them, and their August sales suffered as a result,” Krebs noted, “Chrysler and GM — both hurt by extended factory shutdowns during their Chapter 11 proceedings — had limited inventory to feed Cash for Clunkers, while high-end automakers didn’t have the right products for these buyers.”

The combined monthly U.S. market share for Chrysler, Ford and GM domestic nameplates is estimated to be 42.2 percent in August 2009, down from 45.7 percent in August 2008 and down from 44.2 percent in July 2009.

Edmunds.com predicts Chrysler will sell 86,000 units in August 2009, down 22 percent compared to August 2008 and down 3 percent from July 2009. This would result in a new car market share of 7.4 percent for Chrysler in August 2009, down from 8.8 percent in August 2008 and down from 8.9 percent in July 2009.

Edmunds.com predicts Ford will sell 185,000 units in August 2009, up 22 percent compared to August 2008 and up 13 percent from July 2009. This would result in a new car market share of 15.9 percent of new car sales in August 2009 for Ford, up from 12.2 percent in August 2008 but down from 16.4 percent in July 2009.

Edmunds.com predicts GM will sell 222,000 units in August 2009, down 28 percent compared to August 2008 but up 18 percent from July 2009. GM's market share is expected to be 19.0 percent of new vehicle sales in August 2009, down from 24.7 percent in August 2008 and down from 18.9 percent in July 2009.

Edmunds.com predicts Honda will sell 137,000 units in August 2009, down 7 percent from August 2008 but up 19 percent from July 2009. Honda’s market share is expected to be 11.8 percent in August 2009, flat compared to 11.8 percent in August 2008 and up from 11.5 percent in July 2009.

Edmunds.com predicts Hyundai will sell 108,000 units in August 2009, up 63 percent from August 2008 and up 44 percent from July 2009. Hyundai’s market share is expected to be 9.3 percent in August 2009, up from 5.3 percent in August 2008 and up from 7.5 percent in July 2009.

Edmunds.com predicts Nissan will sell 89,000 units in August 2009, down 18 percent from August 2008 but up 25 percent from July 2009. Nissan's market share is expected to be 7.7 percent in August 2009, down from 8.7 percent in August 2008 and up from 7.2 percent in July 2009.

Edmunds.com predicts Toyota will sell 209,000 units in August 2009, down 1 percent from August 2008 and up 20 percent from July 2009. Toyota's market share is expected to be 18.0 percent in August 2009, up from 17.0 percent in August 2008 and up from 17.6 percent in July 2009.