DETROIT – Ford and General Motors are expected to unveil several new hybrid vehicle models at this month’s North American International Auto Show in a bid to catch up to their Japanese rivals.

Ford Motor Company, the nation’s second-largest automaker behind GM, announced yesterday that it will start selling a hybrid version of the Mercury Mariner SUV this year – a year earlier than originally announced – and begin full-scale production of a hybrid Mazda Tribute SUV within two years. Ford owns about one-third of Mazda Motor Corporation.

The company also said hybrid versions of the upcoming Ford Fusion and Mercury Milan sedans will be on the road within three years. The new vehicles will join the Ford Escape Hybrid, the world’s first gas-electric hybrid SUV, which went on sale last summer.

General Motors is set to introduce an Opel Astra diesel-hybrid concept, which it said will be 25% more fuel efficient than comparable compact diesels. The concept is the first in the collaboration between GM and DaimlerChrysler AG to build hybrid engines.

The company also plans to introduce a hybrid SUV concept called the GMC Graphyte, with an engine system similar to hybrid versions of the GMC Yukon and Chevy Tahoe SUVs, due in 2007. The Graphyte would get 25% better fuel economy but still have the power of a comparably sized SUV, GM said.

GM and Chrysler already sell hybrid pickups, but the systems are less advanced and fuel-efficient than those developed by Toyota Motor Corporation, Honda Motor Company, and Ford.

Toyota, Japan’s no. 1 automaker, said in October it would double the number of Prius hybrid cars for the American market in 2005. The company aims to sell 300,000 hybrid vehicles worldwide by the end of this year. More than 100,000 Priuses have been sold in America since 2000.

Toyota also plans to begin selling hybrid versions of its Highlander and Lexus RX SUVs in America this year.

Last year, Honda began selling its third hybrid car in America, a high-performance version of its popular Accord sedan.

Even as the popularity of hybrids grows, automakers have said that gas electric engines are a transitional technology that eventually will be replaced by hydrogen-powered fuel cells. Experts say that is still at least a decade away, though.

GM said it hopes to start using fuel cells in marketable cars by 2010. Its Sequel concept – roughly the size of the Cadillac SRX – can travel up to 300 miles on its hydrogen supply and accelerate to 60 mph in 10 seconds.

Ford said eight of its hydrogen-powered E-450 buses will debut in Florida in 2006.

The Detroit auto show opens to the public next Saturday.