The numbers are in, and for the Nissan Leaf electric car, they're not pretty.

Despite a boost in its EPA-rated range from 84 to 107 miles, its year-to-date sales of 4,697 units are down 40 percent on the 7,742 that were sold in the same five months last year.

And those were down on the total of 10,389 over the year-earlier total during the first five months of 2014.

DON'T MISS: Plug-in electric car sales for May flat: Leaf struggles despite range boost

A host of reasons for the steady decline is possible, but journalist Brooke Crothers suggested in Forbes that it's all due to what he calls the "Tesla Model 3 effect."

As defined under the more general category of the Osborne Effect, this is essentially a whole host of interested buyers for an existing tech product choosing to postpone their purchases because a new, better, cheaper, more capable product has been announced for some point in the future.

Crothers suggests that the publicity around the 400,000 people who gave Tesla $1,000 each for a place in the waiting list for those Model 3s has convinced many potential Leaf buyers that Something Much Better is just around the corner.

Tesla Model 3 design prototype - reveal event - March 2016

Tesla Model 3 design prototype - reveal event - March 2016

The 200-mile Tesla Model 3 is supposed to go into production some time between July and December next year. Its base price, Tesla says, will be $35,000.

Whether that will happen remains to be seen. Tesla's track record on meeting its dates isn't good, but the company says it has learned from the overly complex and hard-to-launch Model X electric SUV.

Meanwhile, the 2017 Chevrolet Bolt EV is scheduled to go on sale around the end of this year.

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The Bolt EV too will have a 200-mile range, at a base price of $37,500, but it's a small, upright hatchback rather than the sleeker fastback sedan shape of the compact Model 3.

Still, there are lots of other reasons that Leaf sales could be languishing.

(1) It's an aging car

With very few exceptions, a car's highest sales periods are the first two or three years after it's launched. The Leaf is now in its sixth model year, and an entirely new version is due to be launched sometime next year.

2016 Nissan Leaf

2016 Nissan Leaf

(2) It was a polarizing design to begin with

Like the Toyota Prius hybrid over several generations, the Leaf's styling is polarizing. Some like it, some hate it, but it's definitely distinctive.

The problem is that if some of your potential buyers like the car's capabilities but hate the design, you've probably lost a sale. Sometimes inoffensive is best.

(3) The loss of the Georgia electric-car tax credit hurt a lot

Last summer, the state of Georgia killed off its $5,000 income-tax credit for buying a zero-emission vehicle.

CHECK OUT: U.S. Plug-In Electric Car Sales For 2015 Fell Slightly From 2014

Nissan has admitted that the Atlanta metro region was one of its top markets.

The loss of that incentive clearly hurts buyers of $30,000 Leafs more than it does those who pay $85,000 or more for Teslas.

(4) 100 miles still doesn't seem like enough to most buyers.

For the earliest electric-car adopters, a boost from 84 to 107 miles of range means a lot.

2016 Nissan Leaf

2016 Nissan Leaf

But to the general public, 100 miles may still sound too low—especially with "200-mile electric car" in so many headlines (the Model 3 again).

(5) Gas is cheap.

It wasn't initially clear that gasoline prices had a direct effect on plug-in electric car sales, though the correlation is obvious for hybrid cars.

But it can probably now be said that for the segment of electric-car buyers who prioritize low running costs, cheap gas makes the numbers harder to justify.

National average gas price comparison, 2012-2015 (via AAA)

National average gas price comparison, 2012-2015 (via AAA)

Regardless of which reason(s) you choose, the aging Nissan Leaf electric car is facing significant headwinds in a flat U.S. market for plug-in electric vehicles.

Which means that buyers, Nissan execs, and dealerships are all eagerly waiting for the next-generation Leaf to be unveiled and produced.

That likely can't happen too soon.

[hat tip: John C. Briggs]


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