Since the late-2010 beginning of the major manufacturer plug-in car era, the Chevy Volt has been the plug-in hybrid sales king, but this year its crown is in jeopardy.

Toyota’s Prius Prime, which has been rolling out and ramping up in sales, has been nipping at the heels of the Volt all year, and in August it again took a chunk from a small sales lead being held onto by the Volt.

To some, there is not a little irony that the Volt would be threatened by the Prime. On paper, the Volt with 53 miles all-electric range is heads-above the 25-mile Prime – and that EV-like experience is typically why many opt for a plug-in over a regular hybrid. Apparently however, there are just about as many buyers who are willing to opt for the sum total value proposition represented by Toyota’s Prius Prime.

Last month the Prime again led the plug-in hybrid sales board over the second-place Volt by 375 units for a total 1,820 units sold compared to the Volt’s 1,445. For this year to date, Toyota has 13,157 sales and now trails the Volt’s 13,895 by just 738 units – a gap which could be closed if it has just a couple more months of similar Volt-beating sales.

East vs. West

The Detroit-built Volt also costs more than the Japanese Prime, but assuming a full tax credit, the spread is only about $3,000 at sticker – not counting potential discounting and other possible perks to further reduce the difference for the larger-battery wielding Bowtie car.

More specifically, the Volt costs about $34,000 before a $7,500 federal tax credit. The Prime is around $28,000 at entry level and is eligible for a $4,500 federal credit and Toyota was clever in its pricing scheme compared to how it marked up the former (inferior) Prius Plug-in Hybrid’s $30-40k barrier to entry.

The sharpened pencil went so far as to make the Prime attractive next to even the non-subsidy eligible, non-plug-in Prius Liftback. The Prime now starts within the low and high price points for the Liftback, meaning the Prime can be perceived by more tire kickers as a good deal at the Toyota dealer than was previously the case.

Without factoring potential state incentives which may narrow the Volt-Prius difference further, the Volt nets for an effective $26,500 and the Prime is around $23,500.

What do you get in each? Both are positioned like “green cars” are these days – a blend of stylized frugality, and a tip of the cap toward the now requisite fun-to-drive factor.

Both sip fuel in gas-electric hybrid mode, with the icing on the cake being all-electric range so they can run as pure EVs for a stretch, ideally long enough to avoid gas day to day.

On this metric, the Volt beats the Prime’s electric range as mentioned: 53 miles vs. 25, while the Prime beats the Volt in mpg. In gas-electric hybrid mode, the Prime beats most trims of the donor Prius Liftback with 54 mpg, instead of 52, whereas the Volt – a purpose-built “extended-range electric vehicle” – is rated 42 mpg.

Keeping to the bare-usefulness comparison, the compact Volt has less interior space with 10.6 cubic feet cargo volume, and the midsized Prime lets you cram in more stuff with 19.8 cubic feet. The Volt however has seating (theoretically) for five, while the Prime devolved back to four.

From the Driver’s Seat

The 1.8-liter hybrid Prius Prime boasts a modest 121 net system horsepower, compared to the Volt’s 1.5-liter hybrid powertrain rated for 149 horses, and unlike Toyota, Chevrolet provides a torque figure of 294 pounds-feet – respectable.

This is enough to make the Volt feel much more lively when one stomps on the go pedal. With all its torque instantly available from a standstill, the 3,543-pound Volt leaps to 30 mph in just 2.6 seconds – quicker than the 2.9-second Bolt EV – and this satisfies the itch for useable acceleration in these cars’ natural habitat – around town.

In that same mini-drag run, 60 mph comes along a bit less progressively in 8.4 seconds. Not amazing and well short of the Bolt EV’s roughly 6.5 seconds, the Volt is otherwise fleet-footed next to the 3,365-pound Prime, whose walk from 0-60 is comparable to the former Prius, or in the neighborhood of 10 seconds. The Prime is not sluggish feeling, but it’s at the other end of the spectrum from any kind of a hot hatch.

Around corners however is another matter. The first-gen 2011-2015 Volt was a nice handler, and the new one is too even with stock low rolling resistance tires. For its second go-around after the 2012-2015 Prius Plug-in Hybrid, Toyota went and made sure the new Prius handles sharply too.

The Prime’s stiffer “Toyota New Global Architecture” (TNGA) chassis and more-expensive-to-produce (slightly) double wishbone rear suspension make it track in a worthy manner around the bends much better than limp-noodle Prius generations of yore.

Beauty Contest

The Prime has been unofficially declared better looking than the non-plug-in Prius Liftback by a majority vote in the court of public opinion. Their results can be found in random article comments all over the Net, but their approval is only half a compliment. The self-appointed Prius Looks Jurors otherwise declare the regular Liftback hybrid’s image anything but fetching, with a few even reserving expletives, and not saying anything so polite as this.

Fortunately for the Volt, mobs with pitchforks have not burned it in effigy, and let it have a pass. The Volt follows its maker’s strategy of blending into the sea of me-too designs by not just borrowing elements of the Honda Civic and Kia Forte, Chevrolet’s stylists actually lifted much from the bread-and-butter Cruze, but it’s considered snappy looking enough.

Of course you are free to disagree as to which you like more. You know what they say about perceptive beauty, right?

Why Else is the Prime So Threatening?

Toyota originated the Prius hybrid in Japan 20 years ago, the plug-in came along in 2012. Both the Volt and it are second-gen plug-in products – the only fully redesigned plug-in cars sold, actually.

Brand perception however goes a long way in “the second largest purchase the average consumer will ever make,” and, well, how do you think an average consumer in a shopping mall would answer a survey between Chevrolet’s reliability, resale value, and quality, versus Toyota’s?

The Prius in particular has a strong fan base, and solid track record. It’s such a good used car, Consumer Reports a few years back came out and recommended a used Liftback over a new Prius c – because they thought the subcompact c was of cheap quality, and a pre-owned Prius would be a better buy even though used.

This said, sometimes stereotypes are deserved, and sometimes they are undeserved in the case of Chevrolet. More to the point, the automaker has been racking up quality and consumer satisfaction survey awards for a few years now, and the Volt in particular has been afforded white glove treatment.

The U.S. automaker has called the Volt a “niche” product “just like Corvette” – albeit the Volt is a niche in its growing technological portfolio it hopes to undergird continued brand-image improvement, and in short, with the Volt, it has something to prove, and does.

Reliability has been relatively good, and the liquid-cooled 18.4-kWh battery has had a very good reliability and range-holding record – and incidentally, said battery costs Chevrolet more to produce, so a Volt buyer is getting value in this regard. On the other hand, Toyota includes standard its advanced Toyota Safety Sense suite, so that in turn is another value to add to the balance sheet comparing relative merits between the two.

So Will The Volt Be Outsold by the Prime?

The Volt is actually the country’s second-best selling plug-in electrified vehicle this year, and its 13,895 sales through August trails only the Tesla Model S which has 14,700 estimated. Toyota’s Prime plug-in Prius is however third-ranked, and with one third of the year remaining (four months), it’s anyone’s guess, but one analyst is projecting a tie.

That would be Michigan-based Alan Baum, who projects the Volt will garner 21,000 sales, and the Prime will also achieve 21,000 sales.

This is otherwise an educated guess, and realistically, either could beat the other, and in all likelihood, there won’t be a dead-even tie, and one will come out ahead.

Any conjectures on which it will be?