The Big Three automakers and their top two suppliers could cut up to 50,000 jobs over the next four years under tentative union contracts reached last week and still fail to close the competitive gap with Asian and European car makers, motor industry analysts have told the Reuters news agency.

Reuters noted that General Motors, Ford and the Chrysler arm of DaimlerChrysler have now won the right to close or sell at least 10 ageing and under-performing plants, which had been forbidden under previous contracts with the United Auto Workers union.

But, the report added, that might not be enough to hold back the rising tide of foreign car makers, which grabbed record US market share in August and many of which rack up most of their profits from the United States. The Big Three, forced to offer hefty marketing incentives to spur sales, struggle to make a profit on their US automotive operations, Reuters said.

"Unless the Big Three break their pattern of deflation and market share losses, it is likely that each of them will experience reductions in profitability despite their restructuring efforts," Deutsche Bank analyst Rod Lache said in a recent research report cited by Reuters.

Reuters noted that, just as the labour talks intensified in early September, market share for the Detroit-based 'Big Three' fell to a record low of 57.9% of US vehicle sales for August. Foreign car makers dominate car sales, and are gearing up to sell more pickup trucks and large sport utility vehicles, a stronghold of the Big Three, the report added.

Citing summaries of the contracts released by the UAW, Reuters said GM could close one US assembly plant and one parts plant and Ford two of each, while Chrysler won the right to close or sell four parts plants. However, Wall Street had expected more, the report said.

"The Big Three gained some ability to close plants. However, the amount and timing appear to be somewhat disappointing," Morgan Stanley analyst Steve Girsky said in a report cited by Reuters.

In exchange, Reuters said, the union won moderate increases in wages and cash bonuses for its members and held its ground on health care coverage - a typical car worker will earn $US17,400 to $18,500 more during the four-year contract, according to the summaries.

According to Reuters, Goldman Sachs analyst Gary Lapidus said the Big Three and its top parts suppliers could cut up to 50,000 jobs over the next four years, which could raise the productivity at Ford, Chrysler and particularly GM to "world-class standards."

"We are also reasonably certain that it doesn't likely matter," he reportedly added, asserting that productivity gains will be offset by higher cash wages.

Reuters said Lapidus calculated that, under the new contracts, Big Three wages will grow at a compound annual rate of 4.8%, the highest rate in 15 years.

Reuters also said that analysts estimate that the Big Three's inefficient plants and heavy health care and pension expenses won in previous contracts give Japanese car makers a $US1,000 to $1,200 cost advantage on every vehicle they build.

Sean McAlinden, chief economist with industry consultants Centre for Automotive Research, told Reuters the Big Three could end up cutting more than 50,000 jobs. "The union will be lucky if that's all it is. What if market share continues to decline?" he reportedly said.

Analysts also told Reuters that, if the US car makers continue to lose market share, the Big Three can take heart that the UAW showed during the negotiations that it recognises that the future of both the union and the US car industry depends on their collective health.

Reuters noted that, unlike UAW negotiations of the past, the union never mentioned striking during the talks and wrapped up deals in record time, illustrating a united front to make the industry more competitive.

"The talks proceeded in a remarkably amicable fashion. The UAW clearly understands the pressures the companies are under, and that is a good thing," UBS analyst Saul Rubin told the news agency.