Two years ago, we pointed out that several electric cars now on sale were purely "compliance cars," built in minimal numbers purely to comply with California rules that require sales of zero-emission vehicles.

But almost four years after the first Nissan Leaf went on sale in December 2010, it's become pretty clear which carmakers are serious about plug-in electric cars--and which aren't.

DON'T MISS: Electric Cars: Some Are Real, Most Are Only 'Compliance Cars'--We Name Names (May 2012)

We looked at U.S. sales of all cars with a plug--whether battery-electric or plug-in hybrid vehicles--for the 10 months of this year, and calculated what percentage of a carmaker's total sales they represented.

(The exception was BMW, which only started selling its i3 electric hatchback in May--so for that maker, we used only the May-October total sales.)

2014 BMW i3 REx vs Chevrolet Volt comparison [photos: David Noland, Tom Moloughney]

We grouped the cars by maker so that, for instance, General Motors includes both Chevrolet and Cadillac plug-in sales.

And we included compliance cars; even if they're limited in volume, they do have plugs.

Here are the percentages of a carmaker's total U.S. sales this year that are made up of battery-electric, range-extended electric, and plug-in hybrid sales:

Tesla: 100 percent

BMW: 2.3 percent (4,534 of 201,000)

Nissan: 2.1 percent (24,411 of 1.17 million)

Ford: 0.9 percent (18,859 of 2.07 million)

GM: 0.7 percent (17,969 of 2.43 million)

Toyota: 0.6 percent (12,321 of 1.98 million)

Surprised?

A couple of things stand out for us.

First, in just six months, BMW is selling a greater percentage of total vehicles with plugs than any other maker except Tesla.

And if you look just at October sales, the number rockets from 2.3 percent over six months to 3.8 percent for last month alone.

BMW's average for the last three months--netting out the MINI and Rolls-Royce brands, in this case--is an even more impressive 4.9 percent--meaning 1 in every 20 BMWs sold from August through October has a plug.

Second, Ford often doesn't get a lot of credit for its efforts, primarily because it has trash-talked the Ford Focus Electric, its sole battery-electric vehicle.

But the plug-in hybrid Energi versions of its C-Max hatchback and Fusion sedan are logging consistent and respectable sales, with the two combined outselling Toyota's plug-in Prius in eight of 10 months this year.

Finally, the top three makers in terms of percentage all sell battery-electric cars. The second tier all sell vehicles that are partially electric and partially gasoline-powered.

Two other analyses of this question largely support our analysis.

A brand-by-brand review of carmakers' commitment to electric vehicles on PlugInCars.com listed all major automakers alphabetically, evaluating the "street cred" of each one.

2014 BMW i3 and 2014 Tesla Model S [photo: Tom Moloughney]

It cited BMW, Nissan, and Tesla as the most aggressive makers pursuing vehicle electrification.

A second take comes from noted battery skeptic Menahem Anderman, whose perspective stems from organizing the Advanced Automotive Batteries Conference for close to two decades now.

He has a consistent track record of criticizing optimistic predictions of electric-car growth, which has offered a useful counterweight to some of the frothiest projections made a few years back.

Even Anderman has complimented Tesla for its impact on the industry, writing, “Tesla has already shattered many of the [auto] industry’s deep-rooted convictions” about electric cars and lithium-ion battery cost.

Battery Electric Vehicle Efforts by Major Automakers (Anderman, Advanced Auto Batteries, Oct 2014)

Recently, Anderman ranked the major automakers for their efforts in battery-electric vehicles only (he ignored plug-in hybrids and range-extended electric cars).

He puts Tesla at the top, as "committed," followed by the Renault Nissan Alliance, which he views as "developing markets" for electric cars.

Then comes BMW, which he says is "exploring niche markets" with its i3, i8, and future products.

MORE: Tesla Battery Cost: New Report Suggests Model 3 To Cost $50K Or More

Then General Motors, VW Group, and Mercedes-Benz are listed as "compliance +"--fair for GM, which has focused on its Voltec range-extended electric powertrain.

And he notes that BMW, GM, Mercedes, and Volkswagen are all "considering" offering a battery-electric vehicle with at least 200 miles of range.

We'd suggest that Daimler (parent company of Mercedes-Benz) may be the odd man out in that group, with significantly lower commitment to pure electric cars than the others.

Either way, though, it's clear that three companies are most committed to making and selling plug-in electric cars: BMW, Nissan, and Tesla.

The second tier is comprised of GM, Toyota, and (surprisingly) Ford.

The rest? Not so much.

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