Two years ago, the launch of the Porsche Panamera S E-Hybrid produced the first ostensible large luxury plug-in sedan competitor to the Tesla Model S electric car.

The Porsche is a plug-in hybrid, with an electric range of 15 or 16 miles; the Tesla is all-electric, with ranges of 208 to 275 miles.

DON'T MISS: 2014 Porsche Panamera S E-Hybrid: Gas Mileage Review Of Plug-In Hybrid

At the time, many commentators suggested the Porsche would eat into Tesla's sales, giving a new option to luxury buyers who wanted a large plug-in sedan from a prestige brand.

Porsche sells about 100 plug-in Panameras a month, but Tesla's U.S. sales remain substantially higher. (Tesla Motors doesn't release sales breakdowns, so we don't know how many cars it sells each month in each market.)

Still, the theme that plug-in hybrid sedans and SUVs from German luxury brands (Audi, BMW, Mercedes-Benz, and Porsche) pose a threat to Tesla continues to appear.

2014 Porsche Panamera S E-Hybrid, Catskill Mountains, NY, Apr 2015

2014 Porsche Panamera S E-Hybrid, Catskill Mountains, NY, Apr 2015

Recently, writer Drew Winter laid out in industry trade journal Ward's Auto several reasons that he feels German brands will pose major competition for Tesla in the years to come.

We would note that those makers were all far more deeply rattled by the sudden eruption of the Tesla Model S into the global luxury-car market than they'll admit.

Winter's premise is that their sales of profitable gasoline vehicles will subsidize substantial losses on early plug-in products from every luxury brand.

ALSO SEE: Do Tesla Model S And Porsche Panamera Plug-In Hybrid Compete? (Jul 2013)

Now that the Germans (along with Jaguar Land Rover) view Tesla as a genuine threat, he suggests, they are quite prepared to absorb years of heavy losses on their own electric cars to counter the sudden emergence of this new and unexpected competitor.

Structurally, we think Winter is right.

But we think the other analysts, who deem the current generation of plug-in hybrid luxury vehicles viable competition for the Tesla Model S and the upcoming Model X electric SUV, are simply missing the mark.

2013 Tesla Model S and 2014 BMW i3, Hudson Valley, NY, Nov 2014

2013 Tesla Model S and 2014 BMW i3, Hudson Valley, NY, Nov 2014

Driving an all-electric car is so qualitatively different from the off-and-on-engine experience of those first-generation plug-in hybrids that it's a completely new kind of experience.

It's the reason that getting "butts in seats" so buyers can actually experience electric cars is so important: They're not only more relaxing but more fun to drive, for many.

Many people used to driving electric find they never want to return to a car with a combustion engine. And while the Tesla Model S is undeniably pricey, it's also unquestionably the electric car with the fewest compromises.

RELATED: New, Smaller Porsche Four-Door Sedan To Be Electric Only: Rumor

This weekend, we have a BMW i3 REx range-extended electric car to test. And it has reminded us just how disappointing it is to hear an engine switch on after 45 or 50 miles of fast, smooth, soothing electric travel.

The Chevy Volt excepted, no plug-in hybrid provides full acceleration with its electric motor; they all require the engine to switch on. Right there, that's a dealbreaker for many.

Upcoming plug-in hybrids from German makers will likely have electric ranges of just 12 to 25 miles. In winter weather, our Panamera plug-in delivered only 9 miles of electric range before its engine kicked in.

2014 Porsche Panamera S E-Hybrid, Catskill Mountains, NY, Apr 2015

2014 Porsche Panamera S E-Hybrid, Catskill Mountains, NY, Apr 2015

In other words, experientially, the current crop of plug-in hybrids just isn't real competition for what the Tesla Model S has to offer.

As we said of the plug-in Porsche, it's "a nice enough luxury hybrid sedan with a little bit of electric range"--but we view it as "a toe in the water, a first test case to see how at least some electric-only driving works in the real world."

In 2017 or 2018, the German brands will start to launch their own all-electric sedans and SUVs with ranges of 250 to 300 miles. By 2020 or so, there are likely to be half a dozen.

At that point: Game on.


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