Out of the 20 plug-in hybrids now for sale in the U.S., the Toyota Prius Prime and Chevrolet Volt stand heads above, but which will sell better is an open question.

Through July this year, the Prime, which rolled out nationally this year, sits as last month’s top seller with 1,645 July sales, and its year-to-date cumulative 11,337 sales total put it in second place behind the Volt.

Long acknowledged as the country’s best-selling plug-in hybrid, the Chevy Volt managed 1,518 sales last month, and has 12,450 to date.

Next in line is the Ford Fusion Energi, with 703 sales last month, and 5,760 sales this year. Only one other car, the Ford C-Max Energi, has 5,000-some sales, after these are three with 2,000-some year to date, and a bunch with much less than that.

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So the Volt and Prius with a plug are in a bit of a race, if you’d like to see it that way – or alternately one can just say they are contributing to the same cause.

Which may finish first this year is in question, with 1,113 sales separating them and five months to go this year.

Prime Advantages

Neither car is completely heads above the other, but the Prius Prime makes up for its less electric range than the Volt with other attributes explaining why it is as close to the Volt as it is.

These include, but are not limited to, the Prime is priced right. Starting around $28,000 before a $4,500 federal tax credit, and with potential state incentives as the case may be, it can net in the low 20s, below the regular Prius Liftback hybrid.

Even without incentives it’s stickered within the spectrum of the Liftback and a Prius shopper might wonder if it would not make more sense just to go plug-in for how competitively it’s positioned.

In terms of doing what the regular Prius Liftback does, the Prime actually gets 54 mpg, instead of 52 as is the case for most Liftback trims, and has the extra added bonus of 25 miles EV range.

Only a four-seater however, it otherwise handles well, is as powerful, and arguably better looking, if the often-expressed opinion of armchair pundits is any indicator.

The Prime also gives up a bit of space in the back of the hatch, but is otherwise a solid proposition with the “T” brand on the badge that carries a lot of credibility and rides on a long history of reliability and resale value.

These and other objective and subjective measures add up to a car that could dethrone the original plug-in hybrid the Volt, that more than doubles its EV range – and all-electric drive capability is normally the main reason why people buy a plug-in over a regular hybrid.

Volt Advantages

Both the Volt and Prime are the only two now in their second generation, but the Volt has been around longer.

The nameplate originated in 2011, and was revised from 38 miles EV range to 53 miles EV range in 2016.

Boasting more sporty potential, as “green cars” go, it zips to 60 in under 8 seconds – a good couple seconds or more quicker than the Prime.

Like the original Volt that may have provoked Toyota to ensure the new Prius now handles well, the Volt also is pretty fun in the corners, even with low rolling resistance tires and torsion beam rear axle.

SEE ALSO: 2017 Chevy Volt Review – Video

The big 18.4-kWh battery that has a history of being very reliable and range-holding over its life helps provide a lower center of gravity.

On the other hand, said big battery also creates voluminous mass to be worked around down the interior center of the car. In back, middle seating is greatly impeded, and the Volt really is most comfortable for four – and those rear-seat passengers have less legroom than Toyota Prime passengers.

The Volt also stickers for around $34,000 and up before a $7,500 federal tax credit which should last GM through 2018 before that starts to sunset due to its having sold 200,000 plug-in cars in total.

That’s a higher price, but assuming the credit which is $3,000 greater, the net difference is only about $3,000 different at sticker.

Prime price: $28,000 – $4,500 = $23,500 assumed net. Volt price: $34,000 – $7,500 = $26,500 assumed net.

Consider a larger state credit too, and potential dealer discounting, and the difference has come out to less and for that you get a proven extended-range EV that allows 28 miles more EV range than the Prime.

The Volt is a Chevy though, and despite its raving fans, does have to overcome those who shut down at the prospect of paying $34,000-$40,000 plus for a compact Chevrolet.

Analyst’s Projection

The Volt is actually very close to its year to date total last year at this time when it had 12,214 sales compared to this year’s 12,450. The Prime was not for sale last year, and the old Prius plug-in, having been out of production for a while, was a virtual non-entity, so Toyota is starting over this year.

This said Michigan-based analyst Alan Baum has lowered his projection to less than the 24,739 Volts sold for all of last year.

Specifically, he is pegging around 21,000 Volts for 2017 and he estimates the Prime will sell to 19,000 meaning the 1,113-unit gap will only widen over the next five months.

“The Volt will face modest competition from the Bolt and is a year older from its update in late 2015,” observed Baum. “The Prius Prime will grow modestly since its update was more recent, in late 2016.”

Baum’s projection for 2018? Volt: 18,500, and Prime 21,000.

Niche Players

To be sure, both are in a niche, and the decision to go with one or the other comes down to numerous variables above the high spots touched on above.

This said, they actually are selling in volumes on par with the Tesla Model S and Model X which have sold an estimated 12,600 and 10,500 this year.

That means the Model S leads all plug-in electrified vehicles, followed by the Volt and Prime. Chevrolet’s new Bolt also rolling out this year is up to 9,563 sales, ranks fifth, and outsold both the Volt and Prime last month with 1,971 units.

The Tesla Model 3 is due to come soon also, and Baum estimates 15,000 could be delivered before December, and 100,000 in 2018, but meanwhile the sub race with the Prime and Volt is relatively close.

What’s more, rumors are also GM is considering the cancelation of the Volt after this generation.

A “Save the Chevy Volt” Facebook page has already been set up to preserve it, and we’ll see in the meanwhile whether the Prius Prime will outsell the Volt this year.