With 2016 about to arrive, BMW is by far the most advanced of the three German automakers in selling battery-electric cars.

All three makers plan to offer plug-in hybrid versions of most of their lineups by 2020, but BMW has been selling its all-electric i3 five-door hatchback for more than two years now--and in substantial volumes.

Rumors about BMW's next battery-electric vehicles continue to emerge, even as other makers like Audi and Porsche announce electric-car production plans for 2018 and later.

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It's largely accepted that the next electric BMW, likely to be called the "i5," will arrive as a 2018 model, perhaps late in 2017.

There have been conflicting reports about what kind of car it is, though the betting is stronger on a small, all-electric crossover utility somewhat larger than today's i3. (The other alternative is a plug-in hybrid sedan.)

Now Automobile magazine suggests that the 2018 i5 will be followed by an all-electric sedan, about the size of today's BMW 3-Series, that could be called the "i6."

2016 BMW 330e

2016 BMW 330e

If so, that would neatly resolve the contradictory reports about a small electric sedan: There is indeed one being developed, as the i6, but it will come for 2021 after the crossover i5 in 2018.

"The i6 will be built on a new “flat-floor” component set made specifically for EVs and have lots of carbon-fiber bits and pieces," the magazine reports.

The electric sedan is said to have at least two motors, perhaps as many as four, and may use entirely new lithium-polymer cells in its high-capacity battery pack.

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The so-called i6 will arrive sometime during the middle of 2020, Automobile suggests, which would likely make it a 2021 model.

But that's when things get interesting, because by that time the company will also have updated its plug-in hybrid lineup from today's ranges of 15 to 20 miles to double that or higher.

BMW previewed its second-generation plug-in hybrid system more than a year ago.

BMW 5-Series Gran Turismo Power eDrive prototype

BMW 5-Series Gran Turismo Power eDrive prototype

Known as Power eDrive, it allows vehicles to run a majority of their miles on electricity alone--with ranges of perhaps 50 or 60 miles and more powerful electric motors than it uses today.

Then a downsized gasoline engine switches on to provide long-distance travel capabilities in the minority of cases where it's required.

We don't yet know, however, whether Power eDrive cars are all-electric until their batteries are depleted (like the Chevrolet Volt) or whether they would continue to rely on their engines for maximum power even if the battery has capacity left (like today's BMW plug-in hybrids).

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Starting in 2021 or so, the balance of sales between longer-range Power eDrive plug-in hybrids and pure electric vehicles with ranges of 200 to 300 miles will be fascinating to watch.

It's clear that BMW sees its future in electrification. But beyond a range boost for today's BMW i3 for the 2017 model year, we won't see much more until the i5 arrives in a couple of years.

But even as other German prestige brands prepare to bring their first electric cars designed from the ground up into production, BMW is at work on its second and third.

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