Honda had no new products to unveil at this year's Detroit Auto Show, although it did show its hydrogen fuel-cell powered Honda FCV Concept car for the first time in North America.

The company announced, however, that it would produce two all-new plug-in vehicles by 2018: one battery-electric car and one plug-in hybrid.

DON'T MISS: 2013 Honda Fit EV: Video From First Drive Of All-Electric Car (Jul 2012)

Frustratingly, however, that was absolutely all the company was willing to say.

"What we're not sharing is anything else" about either of those vehicles, said Robert Bienenfeld, Honda North America's senior manager for environment & energy strategy, during an hour-long roundtable with reporters.

2014 Honda Accord Plug-In Hybrid

2014 Honda Accord Plug-In Hybrid

The new vehicles will be launched "to ensure Honda’s environmental vehicles remain strong competitors and provide a new sales-volume pillar," in the words of the company's announcement this morning.

Honda will also offer "further applications" of both the two-motor hybrid system it now offers in the Honda Accord Hybrid and Plug-In Hybrid mid-size sedans, and the three-motor hybrid system available in certain Acura sport luxury models.

ALSO SEE: Green Car Reports' Best Car To Buy: 2014 Honda Accord Hybrid (Nov 2013)

It seems likely that the future battery-electric vehicle will take the place of the Honda Fit EV compliance car. Offered only for lease--not purchase--starting in 2012, the Fit EV is now largely gone from showrooms as Honda nears its required total of 1,100 zero-emission vehicles.

Less is known about the plug-in hybrid. Given the number of German luxury SUVs that will introduce plug-in hybrid options over the next two years, however, such a system might logically appear on an Acura crossover utility vehicle.

2013 Honda Fit EV drive event, Pasadena, CA, June 2012

2013 Honda Fit EV drive event, Pasadena, CA, June 2012

Those vehicles include the new Audi Q7 (launched at yesterday's Detroit Show media day as well), BMW X5, and two Mercedes-Benz SUVs: the 2016 GLE (nee ML-Class) and the new GLE Coupe unveiled yesterday in its global debut.

With U.S. gasoline prices at their lowest levels in years, SUVs and crossover utility vehicles in several size classes are taking an increasingly large share of the market.

MORE: When Will Plug-In Electric SUVs And Crossovers Go On Sale?

But carmakers know they must boost the fuel efficiency of these vehicles to meet steadily rising corporate average fuel economy goal from now through 2025--hence the plug-in hybrid versions of the most expensive SUVs, where the higher price of the electric hardware may be less of an impediment to sales.

The production version of the hydrogen-powered FCV Concept will be introduced in the U.S. in 2016, several months after the 2016 Toyota Mirai goes on sale in limited numbers in certain regions of California.

For all the latest information from the show, see our Detroit Auto Show News page.

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