About 600,000 plug-in electric cars have been sold in the U.S. in the past 10 years.

The number for hydrogen fuel-cell vehicles is lower: as of the end of last month, it's below 1,600.

Nonetheless, Honda, Hyundai, and Toyota today offer zero-emission vehicles powered by hydrogen in limited areas of California, and other makers are likely to launch theirs in years to come.

DON'T MISS: 2015 Hyundai Tucson Fuel Cell: Hydrogen Crossover First Drive (Dec 2013)

We were curious to see how our Twitter followers felt about the three entries now on the market.

Those are the Hyundai Tucson Fuel Cell (for which leases started in 2014), the Toyota Mirai (first deliveries in October 2015), and the Honda Clarity Fuel Cell (first delivered last December).

Frankly, our followers don't appear very impressed by any of these three cars.

We specifically asked which of the three was "the most important fuel-cell car so far," naming each of the current entries.

But almost six in 10 respondents chose the "none of the above" answer: "It hasn't arrived yet."

READ THIS: 2016 Toyota Mirai: First Drive Of Hydrogen Fuel-Cell Sedan (Dec 2014)

Hmmmmmmmm.

Of the three cars named, the Toyota Mirai (rated at 312 miles of range) received by far the most votes, at 22 percent.

First 2017 Honda Clarity Fuel Cell deliveries, Torrance, California

First 2017 Honda Clarity Fuel Cell deliveries, Torrance, California

That's more than half of the votes by survey respondents who chose any hydrogen car at all.

The Honda Clarity Fuel Cell (365 miles) got 13 percent of the votes, and the pioneering Hyundai Tucson Fuel Cell (265 miles) just 7 percent.

Part of the apparent lack of enthusiasm in this (very unscientific) poll may come from lack of familiarity with hydrogen fuel-cell vehicles in the first place.

CHECK OUT: GM, Honda set up joint fuel-cell plant, 2020 production goal

Fuel-cell cars remain even more of an unknown to mass-market buyers than do plug-in electric cars, in part because their visibility is limited since they can only be sold where hydrogen fueling infrastructure has been built.

For the moment, that means northern and southern California, with plans to expand into limited areas of the Northeastern U.S. by 2020.

We'll have our drive report on the Clarity Fuel Cell out this week.

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