DETROIT - Detroit's Big Three automakers appear to have decided performance doesn't sell - at least for 1998. Taking up where their Japanese counterparts left off with their home-market Tokyo auto show last October, Detroit automakers blitz the press with an unprecedented message of eco-friendliness at January's North American International Auto Show (NAIAS).

Chrysler Corp., Ford Motor Co. and General Motors Corp. all emphasize high-economy, low-emissions vehicles and concept cars at their hometown auto show, prominently focusing on environmental responsibility as never before.

Although the more critical members of the press speculate Detroit's "green" message is driven by various self-serving ulterior motives - similar criticism was leveled at the Japanese after their recent ecologically focused auto show - Detroit automakers nonetheless appear serious about investing in efficient, low-emissions technology.

Much of the technology underlying the high-efficiency vehicles Detroit's Big Three show at the 1998 NAIAS is derived from Partnership for a New Generation of Vehicles (PNGV) activities to develop an 80-mpg (2.9L/100 km) family sedan. Although each automaker's supercar relies to some degree on similar developments (such as direct-injection diesel engines), each clearly plans to take PNGV ideas in different directions.

The high-mileage concept vehicles are intriguing, but the Big Three openly admit most are at least three years away from ever seeing the road - so there was plenty of production-based, spend-your-money-on-this hardware to see in the meantime.

It was nice just to see GM doing concept vehicles again, after a short hiatus from the practice. The Buick Div. raised the most eyebrows with its hybrid car/SUV Signia, which bears some outrageous lines covering a G-body chassis and a 240-hp supercharged 3.8L V-6. An advanced all-wheel-drive system maintains the required SUV tie-in, although GM says the system doesn't really exist just yet. Buick General Manager Robert E. Coletta says the Signia is a "signal of a new way of thinking at Buick, a test-bed of ideas. We'll be in trouble if we just rely on our existing owners." Amen.

Sport/utility vehicle (SUV) melds with minivan for Pontiac's Thunder, a heftily stretched TranSport minivan that takes the Montana theme a few steps further.

Chevrolet stages the Intimidator, a NASCAR-esque Monte Carlo-based concept that may presage next-generation (1999) Monte Carlo styling direction. Power comes from a supercharged 3.8L V-6, but don't expect a manual transmission.

Ford trots out the Alpe Limited, a concept SUV based on the Alpe Ghia it has shown before. All indications point to the 4-cyl.-powered Alpe as Ford's contender to the Toyota RAV4 and Honda CR-V mini-utes.

Chrysler, of course, captivates the media with its concepts, led by the provocative Chronos, which furthers the styling trend with 1996's Atlantic. The Chronos coupe employs Chrysler's 8L V-10 to drive the 21-in. (53-cm) rear wheels. The retro-style interior offers touches like a personal cigar humidor.

The 2-seat Plymouth Pronto Spyder appears production-feasible as a cut-price alternative to expensive performance roadsters from BMW AG and Porsche AG. The Spyder's V-6 engine is mid-mounted and develops 225 hp to drive the rear wheels. Light weight is the primary technical draw, with body panels made completely of polyethylene terephthalate (PET), a recycled plastic.

Import automakers keep pace with the hometown Big Three by showing several significant concepts. High on the list is Honda Motor Co. Ltd.'s MV-99, a half production/half concept look at the highly anticipated full-size minivan Honda will make in Canada and sell in the U.S. this fall.

Even usually restrained Audi can't resist the temptation of luring customers determined to have an SUV. The Allroad Quattro is a hunched-up half-brother to the A6 Avant station wagon, much in the vein of the Subaru Outback. Audi says a production version should be out later this year.

Mitsubishi Motors Corp. alludes to high-speed trains and human anatomy to describe the "geo-mechanical" styling of the interesting SST GT car. Carbon fiber plays heavily in SST's construction, and insiders allude to styling connections for Mitsu's next-generation 3000GT, including power from direct-injection gasoline engines.

Some of the more significant production cars at the NAIAS include:

n Volkswagen AG's New Beetle is the unchallenged hit of the show. The car goes on sale in the U.S. in March at a base price of $15,200; VW says it hopes to sell 50,000 Beetles in the first full year of production.

Available engines for the New Beetle, to start, will be the ubiquitous 2L 4-cyl. (120 hp) and, somewhat surprisingly, the excellent 1.9L TDI direct-injection turbodiesel I-4.

n GM shows barely disguised "concept" versions of its new full-size pickup trucks scheduled to go on sale this fall. The 1999 Chevrolet Silverado and GMC Sierra will have 6-cyl. base engines and a drastically improved lineup of new, iron-block V-8s based on the all-aluminum LS1 OHV V-8 first launched in the 1997 Corvette.

n GM also unveils its all-new Pontiac Grand Am, a perennial best-seller in the GM family. The '99 model has a stretched wheelbase, yet overhangs are reduced to make for shorter overall length.

n Ford's Lincoln-Mercury Div. unwraps the long-awaited Cougar replacement, a 2-door coupe displaying large portions of the company's New Edge styling direction. The 1999 Cougar sits on the Contour/Mystique CDW-27 platform.

n Chrysler Corp. reveals the 1999 LHS and 300M, the two 4-door sedans that round out the family of completely redesigned LH sedans that began with the 1998 Dodge Intrepid and Chrysler Concorde. LHS goes on sale in the U.S. this fall powered by a new, all-aluminum SOHC 3.5L V-6.

n Toyota Motor Corp.'s Lexus RX300 SUV is built on a unibody chassis and is aimed directly at Mercedes-Benz's overwhelmingly successful M-Class SUV. Its base price of $31,550 slightly undercuts Mercedes, but the base RX300 is front-drive; M-Class models are full-time all-wheel drive (AWD) systems.

Toyota's Solara makes its debut as well, the company's return to a coupe bodystyle of the Camry, although its sheetmetal is at least a bit more engaging than the Camry's.

n Mercedes, incidentally, knows how to admit a mistake; journalists complained when the SLK roadster arrived in North America without a manual transmission. At NAIAS, the company relents and says it will offer a manual this fall as a '99. M-B says it expects 5-speeds to account for 15% to 20% of total U.S. SLK sales.