Last month marked a major milestone for U.S. sales of plug-in electric cars: the 100,000th Chevrolet Volt was delivered.

It's the first car with a plug in any segment to reach 100,000 units, and Chevy's justified in celebrating the occasion with a press release and a bit of fanfare.

Both the Volt and the Nissan Leaf battery-electric hatchback went on sale in December 2010, and the Leaf led the Volt in total sales for a majority of the five and a half years since then.

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But the well received second-generation Volt plug-in hybrid—winner of the Green Car Reports 2016 Best Car To Buy award—has surged past the Leaf, outselling it for each of the last 10 months.

Volt sales in July were a whopping 2,406, its best month since August 2014, for a seven-month total this year of 12,214, and a grand total since December 2010 of 100,964 sales.

The Leaf, on the other hand, logged 1,063 deliveries for a year-to-date total of 6,856.

2016 Nissan Leaf

2016 Nissan Leaf

Total U.S. sales for the Leaf since launch are 96,447, meaning it should cross the line in October or November if that pace continues.

The third best-selling electric car in the U.S. is likely the Tesla Model S, but its maker refuses to release monthly sales or break down quarterly sales by country, so we don't know those numbers exactly.

And fourth on the list of modern plug-in vehicles is still the now-discontinued Toyota Prius Plug-In Hybrid, at more than 42,300 in total. It will be replaced by the Toyota Prius Prime, which goes on sale later this year.

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The highest sales of plug-in hybrids now come from Ford, whose Energi versions of its C-Max compact hatchback and Fusion mid-size sedan together have outsold Nissan for many months running, and in many months Chevrolet as well.

Contrary to the pattern over the last several months, Fusion Energi sales fell to 1,341 while the C-Max Energi logged 755 deliveries, which was narrowly its best month since way back in August 2014.

Together, the two cars totaled 2,096 sales, meaning that Ford and Chevy have now swapped the lead in plug-in car sales a few times this year alone. Nissan lags behind.

2016 Ford Fusion Energi

2016 Ford Fusion Energi

The BMW i3, which will get an updated 2017 model with 50 percent more range starting next month, sold a remarkable 1,479 units, its highest monthly total since July 2015.

That brings year-to-date sales to 4,359 and total sold since its U.S. launch in 2014 to 21,475.

Deliveries of the Volkswagen e-Golf for July were a robust 344, its best month this year so far, for a seven-month total of 1,799.

But the e-Golf was just slightly beaten by its VW Group stablemate, the Audi A3 e-tron, at 349 units, giving the German luxury make a total of 2,291 sold for the year to date.

Lower-volume vehicles

The majority of battery-electric and plug-in hybrid models sold in parts of the U.S.—usually meaning California—remain low in volume, usually under 200 units a month.

2016 Mitsubishi i-MiEV Quick Drive - Portland OR - July 2015 [photo: Doug Berger]

2016 Mitsubishi i-MiEV Quick Drive - Portland OR - July 2015 [photo: Doug Berger]

The tiny Mitsubishi i-MiEV racked up 20 sales, or as many in July as in the previous six months put together, for a seven-month total of 40 deliveries.

Company spokesman Alex Fedorak attributed the relative sales surge to "aggressive cash-back incentive package" and a group purchase by the city of San Jose, California.

The Mercedes-Benz B-Class 250e (nee Electric Drive) logged another 50 sales, for a seven-month total of 360, far behind its 2015 pace at the same time.

2017 BMW i8

2017 BMW i8

The BMW i8 saw sales of 166, bringing total year-to-date sales of the stylish plug-in hybrid coupe with the bird-wing doors to 786.

Meanwhile, sales of the Cadillac ELR range-extended electric coupe, the small, pricey luxury vehicle based on the first-generation Volt underpinnings, continue to dwindle.

Now effectively a dead model, the ELR sold another 15 units last month, bringing its 2016 total to 511 and its lifetime sales to just 2,851.

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In its second month on the market, sales of the plug-in hybrid Mercedes-Benz GLE 550e rose from 16 to 30. The company also sold one additional S 550e plug-in hybrid sedan.

The Ford Focus Electric continues to sell only in double digits, before a planned range upgrade to roughly 100 miles for the 2017 model year.

A mere 58 electric Focuses found buyers in July, bringing the seven-month total to just 504.

Meanwhile, the Chevy Spark EV continues to do more volume this year than last, with July sales of 333 bringing the year-to-date total to 2,112 as Chevy gears up for first deliveries of the Bolt EV in the fourth quarter.

This story will be further updated as data arrives from the last few automakers with low-volume plug-in vehicles, including BMW, Porsche, and Volvo.

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