Diesels seem likely to gain U.S. market share in light trucks and SUVs, hybrids are at least holding their own, and of course sales of plug-in electric cars are rising steadily.

Wait...are we missing a green-car technology?

As an article in The Los Angeles Times points out, natural-gas powered passenger vehicles remain the "neglected stepchild" among vehicles with alternative powertrains.

DON'T MISS: Where Are Natural-Gas Vehicles Most Popular And Most Numerous?

Under two different model names, Honda has now been selling its Civic compact sedan with a natural-gas option in certain states for almost 15 years.

Sales have remained stubbornly between 1,000 and 3,000, and the cars continue to be bought primarily by fleet buyers who can refuel them at centralized natural-gas fueling stations that they own and operate.

2015 Chevrolet Impala Bi-Fuel Natural Gas

2015 Chevrolet Impala Bi-Fuel Natural Gas

The article in the Los Angeles Times notes that a bi-fuel Chevrolet Impala that can run on natural gas or gasoline will soon be available at selected Chevy dealers.

That car, too, seems unlikely to move the needle significantly on sales of natural-gas passenger vehicles.

As always, the issue turns out to be higher vehicle cost combined with a lack of fueling infrastructure.

ALSO SEE: Why Aren't Natural Gas-Powered Long-Haul Semi Trucks Selling Better?

The U.S. has roughly 1,000 natural-gas fueling stations, but only about half of those offer access to the public. The rest are on private property, often on fleet bases for private, public, and public-transit locations.

Nonetheless, Honda perseveres in its position as the longest-standing seller of natural-gas passenger cars.

2014 Honda Civic Natural Gas

2014 Honda Civic Natural Gas

The 2015 Honda Civic Natural Gas model has been updated with additional features (as has the rest of the Civic lineup).

Honda has belatedly added some luxury features to the Civic Natural Gas, including leather seats and an uprated six-speaker audio system.

MORE: Prototype Natural-Gas Vehicles Use Gasoline As Range Extender

This addresses the desire for a less Spartan model among the private buyers who lease or buy the natural-gas Civic solely for its access to California's carpool lane.

A few years ago, while road-testing the new 2012 Civic Natural Gas, we spoke to just such a buyer (who was then waiting patiently for delivery of his Tesla Model S, which is eligible for the same sticker).

The missing link for expanded natural-gas car sales seems to be a home-refueling device that could fuel such a car overnight from the low-pressure natural gas supply lines that now reach roughly half of U.S. households.

2015 Chevrolet Impala Bi-Fuel Natural Gas

2015 Chevrolet Impala Bi-Fuel Natural Gas

But the cost for such a device would have to be less than $1,000 for the numbers to pencil out: The fuel itself is much cheaper on a per-mile basis, but the cars are pricier and adding a home compressor to fuel them only increases that hurdle.

Natural gas likely has better prospects for commercial vehicles, including long-haul semis, which refuel at a much smaller number of locations.

Even there, however, sales have been less than stellar--meaning stepchild status may continue for a while to come.


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