Poring over monthly sales figures for plug-in electric cars--and our six-month summary--the data points out an unexpected fact.

Did you know that pure battery-electric cars actually outsold plug-in cars that also have engines?

From January through June of this year, the combination of 9,839 Nissan Leafs, 882 Mitsubishi i-MiEVs, and approximately 9,400 Tesla Model S cars (plus 1,700-odd compliance cars and others) exceeds the total of 18,335 plug-in hybrids and Chevrolet Volt range-extended electric cars.

Slightly different six-month sales totals from the Electric Drive Transportation Association tell the same story.

EDTA reports 22,712 battery-electric cars (we presume they use different estimates for the monthly sales that Tesla doesn't report) against the same 18,335 plug-in hybrids and range-extended electrics that we tallied.

2013 changes everything

That wasn't what happened in 2011 or 2012.

And according to market analysts, that wasn't how it was supposed to happen, either.

The long-held assumption has been that the limited range of battery-only electric cars would doom them to permanent second-class citizenship.

To alleviate range anxiety, even the most avid electric-car advocates would opt for a car whose gasoline engine provided the ability to travel hundreds of miles without waiting hours to recharge.

If you simply look at the Nissan Leaf--by far the bulk of the affordable battery-electric cars--that's largely true.

2012 Tesla Model S

2012 Tesla Model S

All about Tesla

All of the difference, of course, comes from Tesla Motors [NSDQ:TSLA].

A year ago, the company had barely delivered its first production Model S--and few analysts expected it to achieve its long-held goal of selling 20,000 or so cars a year.

We won't learn the final Model S second-quarter sales total until sometime next month, when Tesla issues its quarterly results.

But the company appears to be on track to hit 20,000 sales globally, once cars now en route to Europe start adding to continuing U.S. sales.

Three new plug-in cars remain to hit U.S. dealers between now and December: the Fiat 500e (this month), and both the 2014 Mitsubishi Outlander Plug-In Hybrid and 2014 Cadillac ELR sometime before the end of the year.

But we don't think any of those three will move the needle appreciably.

Which plug-in predominates?

What will largely determine the ratio of battery-electric to plug-in hybrid vehicles is how aggressive Nissan chooses to be on Leaf sales for the rest of the year.

It has averaged roughly 2,100 sales per month since U.S.-built 2013 Leafs started shipping in volume last March--but could it up that to 3,000?

We're frankly not sure what the balance will be a year from now. But what do you think: Will battery-electric cars (led by Tesla) continue to outsell plug-in hybrids?

Leave us your thoughts in the Comments below.


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