Greater electric-car adoption requires both dealers and carmakers to be strongly committed to selling plug-in vehicles.

Years of anecdotal evidence from shoppers shows such commitments are often lacking—and that  has now been confirmed in a wide-reaching report issued by the Sierra Club.

The organization recently conducted what it calls the "first-ever multi-state study on electric vehicle shopping experience."

DON'T MISS: Most Car Dealers Are Lousy At Selling Electric Cars: Here's Why (Nov 2015)

It concluded that both carmakers and dealers can do much more to improve the experience for consumers shopping for electric cars.

The assessment is based on a survey of 308 volunteers, who inquired about electric cars in calls or visits to dealerships in 10 states.

Those 10 were the "ZEV" states that have adopted California's stricter emissions standards.

2016 Ford Focus Electric

2016 Ford Focus Electric

Beside California, the states include: Connecticut, Maine, Maryland, Massachusetts, New Jersey, New York, Oregon, Rhode Island, and Vermont.

Major issues described in the full report (PDF) included everything from salespeople who lacked basic knowledge about electric cars to a lack of available cars on dealer lots for test drives.

Of the dealerships visited that had at least one electric car on the lot, survey respondents said that one-third of the time, salespeople did not mentioned the federal, state, or local incentives that might be available for a given model.

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In addition, only about half of salespeople provided any information about how to find charging stations for electric cars on the road during long trips.

Many dealers that had electric cars on their lots also didn't seem that interested in letting potential buyers know about them.

The survey noted that 42 percent of the time, electric cars were either "not prominently displayed" or were only "somewhat prominently displayed."

2017 Chevrolet Volt

2017 Chevrolet Volt

At 14 percent of dealerships, respondents were told that cars weren't even sufficiently charged to provide a test drive on electric power.

Specifically, this was the case at 22 percent of Chevrolet dealerships visited, and 21 percent of Ford dealerships, according to the report.

MORE: Tesla Stores don't hard-sell shoppers; this baffles dealership groups

The situation was somewhat better in California, which accounts today for the majority of U.S. electric-car sales.

The Golden State is the only one with a zero-emission vehicle mandate that requires carmakers to sell these cars.

Among dealerships visited by Sierra Club volunteers, those in California had twice the average number of electric cars on their lots as those in the nine other states surveyed.

2016 Nissan Leaf

2016 Nissan Leaf

And dealers in California had no electric cars on their lots far less than in the other nine states—2.5 times less frequently, in fact.

That state has long been both a pioneer in cleaning up vehicle emissions, and consequently an outlier when it comes to adoption and promotion of green cars.

The report also recommends a number of actions for carmakers to take to boost the ease of shopping for and selling plug-in electric cars.

They include providing increasing plug-in car inventory to more dealers in more states to make test drives easier (at terms dealers will accept), and requiring regular training of dealer salespeople on best practices in selling plug-in cars and informing buyers about incentives, charging infrastructure, and more.

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