Car dealers may be the same all over the world, at least when it comes to electric cars.

In 2014, Consumer Reports did a study that showed 50 out of 85 dealerships visited nationwide either outright discouraged its secret shoppers from buying electric cars or tried to talk them into buying a gas or diesel model instead. Few answered questions correctly about electric car incentives, charging, or battery warranties.

A study in February by McKinsey & Co showed a similar trend in Beijing and Shanghai, where dealer salespeople suggested gas cars before they recommended electrics, despite large incentives to buy electric cars in China and the country's goal eventually to ban internal-combustion cars. 

Now another study, by the journal Nature Energy showed that dealerships in Denmark, Finland, Iceland, Sweden, and electric-car friendly Norway failed to mention electric cars to secret shoppers, and some wouldn't even admit that they sold electric cars.

One salesperson at a dealership in Scandinavia told a customer who asked about buying an electric car, "Do not buy this; it will ruin you." Another would-be customer was gently steered away from an electric car because the salesperson insisted—wrongly—that it would take two days to drive 220 miles.

READ THIS: Many Car Dealers Don't Want To Sell Electric Cars: Here's Why (2014)

Similarly to the other studies, the biggest problem seemed to be a lack of salesperson knowledge about the cars. (Consumer Reports found that some automakers who had made bigger investments in electric cars did a better job of training dealers and sales people to sell them.)

If salespeople at car dealerships don't encourage shoppers who are already interested in buying electric cars, it could be detrimental to national goals to reduce energy use and emissions from transportation—especially now, say the European researchers.

Electric car adoption is at a tipping point, they say, where they need to transition from early adopters to a larger "early majority" group of mainstream consumers. These consumers may not be as well-versed in electric-car technology and will be more reliant on dealership personnel to give them accurate information to make the best decision.

If salespeople turn away customers interested in electric cars, though, or steer them toward more conventional models, electric cars may never get over that hump to mainstream buyers, no matter how much range they have.