Innovation can be a hard concept to define as it relates to electric cars.

Sure, there are the powertrains and structural designs of the vehicles themselves—including new proportions for the cabin enabled by the compact running gear and battery packs under the floor.

But there are also many factors outside the car itself: education and marketing for car shoppers, charging networks to enable longer trips, the role of public utilities, and a lot more.

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Today, China is the world's largest electric-car market, just as it is the largest new-vehicle market too—almost twice as large as that of the United States.

That country wants to take a commanding lead in global production of not only photovoltaic solar cells and lithium-ion battery cells, but also plug-in electric vehicles.

Last September, its government said officially that it was assessing in what year it would ban the sale of new vehicles with internal-combustion engines.

That led us to wonder where innovation across all the different areas of the electric-car ecosystem would be more intense.

And we turned it into one of our weekly polls, asking our Twitter followers where they thought we would see the most innovation in coming years.

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Perhaps not surprisingly, China was the resounding answer, chosen by more than half (57 percent) of all participants.

The United States, the next most popular choice, received only 17 percent of the votes.

Buick Velite 5 to be sold in China (Chevrolet Volt in North America)

Buick Velite 5 to be sold in China (Chevrolet Volt in North America)

Europe received 12 percent, though it was slightly surpassed by the 14 percent of responders who opted for "all of the above," which is to say China, the U.S., and Europe would all see innovation, presumably at roughly equal rates.

Given China's dire air quality in most major cities, and the public agitation it causes, it's not surprising that vehicles with no tailpipe emissions are seen as both a way to cut emissions over time and a potential source of strength for the dozens of Chinese automakers.

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We wonder, however, exactly what the resounding expectation that China will be the source of electric-car innovation says about both the North American vehicle market and the companies headquartered here.

As always, please note that our Twitter polls are far from scientifically valid, due to small sample size and self-selection by those who choose to participate.