DETROIT (Reuters) - U.S. automakers continue to rely on price breaks to draw customers into showrooms. This week two companies announced generous incentive plans to help reduce inventories of 2003 vehicles and jump-start sales of 2004 models.

The Chrysler unit of DaimlerChrysler (DCX: Research, Estimates), seeking to halt a steady decline in its U.S. market share, said Tuesday that it will begin offering "aggressive" new consumer incentives on most of its 2004 model year vehicles.

Chrysler spokesman David Elshoff said the company would offer cash rebates and several interest-free financing plans as part of a sales program beginning Wednesday and running through Oct. 31.

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"We're known typically as a follower," Elshoff told Reuters, referring to the dominant role General Motors has played in Detroit's price war since it began nearly two years ago.

"We're going to try to get out ahead of the curve and be aggressive with incentives," said Elshoff, who noted that most of Chrysler's 2004 models were already in dealership showrooms.

For its part GM (GM: Research, Estimates) rolled out a new consumer incentives program Wednesday, extending Detroit's price war into a third straight year.

The new program, which runs through Sept. 30, maintains the hefty cash rebates and interest-free financing deals that GM has used all summer to clear out its inventory of 2003 models.

But it also spreads incentives across a broader array of 2004 model year vehicles, the growing focus of attention at dealerships as the industry heads into the fall selling season.

Chrysler has made its deals on 2004 models slightly less generous than what it offered on 2003 models, but Elshoff said buyers could still get rebates of up to $3,000 on many new cars, trucks, minivans, and sport utilities and zero-percent financing for up to five years.

The company also extended incentive offers on its 2003 models through Oct. 31, Elshoff said.

Despite offering cash rebates of up to $4,500, Detroit's automakers have lost about 1.5 percentage points of U.S. market share since the start of the year, mostly to Japan's Toyota Motors (TM: Research, Estimates).

Chrysler lost $1.1 billion in the second quarter due to the high cost of incentives. But as a mass-market automaker, with a vehicle lineup in need of fresher models to attract new buyers, analysts say it has little choice but to match GM on discounts.

GM introduced interest-free financing to bolster sales soon after the Sept. 11, 2001, attacks in New York and Washington. It has led a relentless but profit-gouging discount war with its smaller cross-town rivals, Ford (F: Research, Estimates) and Chrysler, ever since.