August new vehicle sales volume (including fleet business) in the US is forecast at 1.42m units, down 4.5% decrease year on year but up 8.7% from last month, according to analysts at Edmunds.com.

"Early in August, sales were dismal. To generate showroom traffic, most automakers introduced incentives programmes midway through the month," said Edmunds' industry analysis head Jesse Toprak.

"That effort was relatively successful, but the uncertainty in the housing market is likely to continue suppressing consumer demand for new vehicles for some time."

Edmunds estimates the combined monthly US market share for Chrysler, Ford and General Motors domestic nameplates at 49.6% this month, down from 53.5% a year ago, but up slightly from 49.4% last month.

"Automakers here in Detroit are quietly wondering how bad it is going to get - and whether the picture will improve in 2008," added Michelle Krebs, senior editor of Edmunds' AutoObserver.com.

"Executives will be facing some tough decisions, given the economic trends and the impending union contract negotiations."

Edmunds expects unit volume at each of the Detroit's 'Big Three' automakers to fall this month while sales by the Japanese-owned top three - Toyota, Honda and Nissan - will be up a few percentage points.

US automakers are expected to announce August results on 4 September.