DETROIT – Honda Motor Co. Ltd. must be causing the Big Three to break a sweat yet again.

The Japanese auto maker dropped a bombshell here at the North American International Auto Show by announcing a Honda Accord with a hybrid drivetrain that includes a cylinder-deactivation equipped V-6 gasoline engine will be on sale in the U.S. by the end of this year as an ’04 model.

In addition, Honda’s all-new ’05 Odyssey minivan, arriving this fall, also will have the cylinder-deactivation V-6, which can shut down one bank of cylinders during cruising speeds.

Honda President and CEO Takeo Fukui says the hybrid Accord will be equipped with Honda’s Integrated Motor Assist (IMA) hybrid system, which powers the Civic Hybrid, as well as an all-new V-6.

Fukui says the new engine, when paired with IMA, will be more powerful than Honda’s award-winning 3L V-6 SOHC, which generates 240 hp in the Accord coupe, yet will achieve fuel economy equivalent to a 4-cyl. Civic, between 30-38 mpg (7.8-6.1 L/100km).

Toyota Motor Corp.’s similarly sized all-new ’04 Prius, however, will remain the mileage king, achieving a combined federal fuel-economy rating of 55 mpg.

Fukui concedes the Accord hybrid will not compete with Prius on fuel economy because he considers the Accord hybrid a “totally different concept” altogether. “On actual road driving,” Fukui says, “I think it’s very good, especially on the highway.” The Prius, on the other hand, achieves its best fuel economy in stop-and-go city driving.

Pricing has not yet been set for the hybrid Accord, which initially will be assembled in Japan, Fukui says. The company expects annual sales volumes of the hybrid Accord to exceed that of the Civic Hybrid, which are about 20,000 units.

The Accord Hybrid is Honda’s third hybrid, following the Insight (1999) and Civic Hybrid (2002). The U.S. Big Three’s first hybrid, the Ford Escape, is expected this summer.

Cylinder deactivation, which allows certain cylinders to sit idle during highway cruising and other driving conditions, first was offered by General Motors Corp. in the 1980s, but the engine drew widespread criticism.

Honda calls its technology Variable Cylinder Management, which first appeared on the Inspire sedan (similar to Accord) in Japan in mid-2003.

This year, GM also is bringing back the technology, introducing its Displacement on Demand (DOD) system as standard on the ’05 GMC Envoy XL and Envoy XUV, equipped with a 5.3L V-8, the company says. One bank of four cylinders will shut down when not needed to produce power. (See related story: GM to Debut Three New Engines)

GM will extend the technology to 6-cyl. engines next year. The first V-6 with GM’s DOD system as standard will be an all-new 3.9L V-6 in the ’06 Chevy Malibu. The same engine, with DOD as standard, will be offered later in the Pontiac G6, which replaces the Grand Am.

GM says DOD improves fuel economy in its V-6 and V-8 engines by 6% to 8%, according to the Environmental Protection Agency test cycle. In some driving cycles, however, GM has achieved 20% fuel-economy gains with DOD.

GM will roll out DOD on the 5.3L V-8 in a number of other SUVs, and the same technology eventually will appear in pickups as well, the auto maker says. By 2008, GM says 2 million of its vehicles will have DOD-equipped engines.

While Honda rolls out cylinder deactivation for overhead-cam engines, GM’s production engines with DOD will be limited to overhead-valve architectures. GM has shown a DOD system for overhead-cam engines but hasn’t committed to production.

Honda also says it has developed its own fuel-cell stack and will introduce it in 2005 in a version of its FCX fuel-cell vehicle. The new stack is compact and delivers higher performance with increased range and fuel efficiency, reduced cost and the ability to start in below-freezing temperatures, Honda says.

Honda says it will build 30 FCX vehicles over the next few years. (See related story: Toyota and Honda Lease First Fuel Cell Vehicles)