Extended-range electric vehicles, or EREVs, are having a moment.

The newest examples are the electric Scout Terra truck and Traveler SUV, unveiled last month and due in 2027. Their debuts came with a surprise: Scout Motors will offer an optional feature called the Harvester, which adds a gas engine to enable longer-distance driving. The range of the battery-electric Scouts was quoted at up to 350 miles, but the Harvester is to offer 500 or more miles—and to allow towing without having to recharge every 100 to 200 miles.

Photo by: Scout Motors

Scout Terra Electric Pickup Truck

It’s no wonder that Scout saw such huge customer interest in those models specifically. In an era when many electric vehicle newcomers still have range anxiety, the EREV seems like the ideal solution. 

More formally known as series hybrids, EREVs are battery-electric vehicles that add an onboard generator to recharge the battery, extending their range. Those generators are gasoline engines that burn fossil fuels to power the generator. Their engines are not mechanically connected to the drive wheels, differentiating them from plug-in hybrids—in which torque from an electric motor and a gasoline engine combines to power the wheels.

So an EREV can be “fueled” by plugging it in to recharge the battery, by filling the gas tank to run the generator that charges that battery, or both. Several new EREVs should be coming to market in the next few years, including the 2025 Ram Ramcharger truck, the aforementioned Scout truck and SUV, most likely some new models from Hyundai and more.

Why are automakers doing this? Because the EREV setup allows them to essentially build EVs on EV platforms, shove in a gas engine to boost their range—and then, perhaps over time, do away with the gas engine entirely as shoppers get more comfortable with battery electrics, the charging infrastructure grows out, and battery range continues to rise. It’s kind of a win-win: a customer gets what’s essentially an EV with an EV-like experience, but can still rely on gas power to avoid range anxiety. And the car companies can better plan for the future at a time when so much feels up in the air thanks to new regulations, up-and-down electric sales and the uneven path to a (hopefully) mostly gas-free tomorrow. 

Unfortunately, it’s not quite that simple. If car companies see EREVs as the medium-term future of internal combustion, that plan depends on people actually using them correctly. 

An EREV platform from BYD’s Yangwang brand in China. Note the battery in the floor, the front and rear motors, and the transparent image of an ICE engine upfront.

Like PHEVs, EREVs May Have A ‘Plug Problem’

For a Harvester-equipped Scout, a majority of its 500-plus-mile range is likely to be provided by gasoline. The battery of an EREV truck will be smaller, with a lower energy capacity, than that of its full EV version. If the Scout BEV delivers up to 350 miles of battery range, let’s say the extended-range model comes in at 150 to 200 miles. So 300 to 350 miles of those 500+ miles are covered on gasoline. Given the speed of filling a gas tank against recharging—even DC fast charging at 800 volts—which are truck owners more likely to do?

Unfortunately, no data today suggests owners of new EREVs will plug them in regularly for most of their miles… or perhaps at all. They may do so, but we simply don’t know. Today, the lack of data for the closest analog for EREVs—the growing number of plug-in hybrids on sale—does not lead to encouraging conclusions.

Photo by: InsideEVs

Hyundai offers details about future EREVs.

As I wrote for InsideEVs in July, the majority of PHEV makers flatly refuse to disclose data on whether they’re plugged in, how often, and what percent of overall miles are covered using grid electricity rather than gasoline. Some just ignore the plug by dubbing the PHEV a “Hybrid” model, e.g. Chrysler Pacifica. Others start the car in hybrid mode, even with a fully charged battery, meaning the owner must specify EV mode every time it’s turned on if they want all-electric drive.

In that light, it seems like magical thinking to believe EREVs will be plugged in as designed. Full, comprehensive, aggregated data is the only answer. Anecdotes no longer suffice.

Will Most Scouts Run On Gasoline?

Scout says roughly two-thirds of its early reservations are for the Traveler SUV, with one-third for the Terra truck. That aligns with Rivian’s sales: it now delivers more R1S utility vehicles than it does R1T pickup trucks.

Photo by: Scout Motors

Scout Traveler Electric SUV

But despite multiple queries from InsideEVs, Scout declined to say what official percentage of its reservation pool had specified the Harvester EREV option. “The Harvester range-extender, connection-focused features like the bench seat, and a return to tactility and utility are resonating with consumers, and we’re seeing that enthusiasm reflected in reservation counts,” is all company officials will say, which does imply a good deal of interest. 

It’s possible that percentage may be high, at least judging from the several hundred participants who responded to a poll in a forum for future owners of the new Scout. According to this publication’s report on the results in late October, 81% of those who have entered their order information have opted for the Harvester EREV.

That’s a small sample that suffers from selection bias: owners motivated enough to join a forum to talk about their future vehicles may not represent the full buyer pool. But if four out of five electric Scout owners feel the need for gasoline backup, even with 300+ miles of battery range, the lure of fossil fuels may remain strong for full-size truck buyers.

“Probably”

Anecdotes don’t suffice, but here’s one that could be indicative: While covering the Scout launch event, I was lucky enough to speak to the proud owner of the very first International Scout ever built in 1960. I asked him what he thought of the new Scouts after the debut. He loved them, he said, and planned to order one that evening for his wife. 

“Which model, the battery-electric or the range-extended one?   

“Oh, the hybrid,” he said.

Would he plug it in? He paused.  

“I don’t know. Probably.”  

Oh.

Clearly owners of historic Scouts—all vehicles 40 or more years old—aren’t the target market. They’re window-dressing for authenticity. Most Scout Travelers will be bought by upscale families to haul kids and stuff among suburbs, just as other EV crossovers and SUVs do. A Scout executive quietly admitted as much to me in a hallway conversation. 

Unless we see data that those families regularly plug in their current PHEV crossovers, it’s hard to assume they’ll do the same for EREVs. 

Scout Terra Concept with Harvester

Let’s be clear: The distinction between an EREV and a PHEV matters only to EV advocates and auto engineers. It matters very little to mass-market buyers. They perceive any vehicle with a gas engine and a battery as a “hybrid.” Some may not know about the plug at all; others may have good intentions that wane over time.

A Harvester Or Ramcharger Are Not A Volt

Perhaps EREV buyers, with more than 100 miles of electric range, will recognize what Chevy Volt owners did with half that range: It’s possible to cover the majority of your miles on grid electricity, only refueling once a month or so. European data suggests that the higher the electric range, the more likely a PHEV is in fact likely to be plugged in. 

But Volts were largely used as single-person commute vehicles; owners expect their full-size trucks to haul heavy items, tow massive trailers, and so on. Will the ease of gasoline for those duties condition owners to fill up their Scouts a majority of the time? We don’t know.

The Harvester EREV version of the Scout followed the Ram 1500 Ramcharger, announced in November 2023. It’s a full-size Ram 1500 REV battery-electric pickup with a 3.6-liter V6 engine added to power a generator, giving it 500 or more miles of range—for towing and road trips. 

Scout won’t deliver its first vehicles until 2027, while recent delays in the Ram 1500 REV launch suggest the Ramcharger may arrive near the end of 2025 or sometime in 2026. So we’ll have to wait a while to understand how the vehicles are used in the real world. Regrettably, earlier EREVs provide limited wisdom into how owners of EREV trucks will behave.

The Volt was the best example of a vehicle that ran exclusively on electricity until its battery depleted, then switched on its engine to give it a few hundred more miles of range. Volts drivers loved them, and charged them incessantly. The Volt wasn’t technically an EREV, because its engine output could clutch directly into the drivetrain under some circumstances. The important part, though, was that it behaved like one. And its bleeding-edge owners took advantage of it; they loved their Volts, and still do.

First-generation Volt owners, with 35 to 39 miles of electric range, covered 63% of their miles on electricity. The second generation, with 53 miles of EPA-rated range, had rates as high as 80%. 

But Volt owners were among the earliest of early adopters. They tended to educate Chevy salespeople on what the car was, how it worked, and why it was a great alternative to, say, an 84-mile Nissan Leaf. (Volts covered more miles on electricity than Leafs did, despite lower battery ranges.) 

That’s a big challenge for Scout, or any other automaker, is due to face in the EREV era: at a time when they’re all struggling to get drivers to understand how EVs work and can’t rely on their dealers to do so, this is yet another powertrain technology that has to be taught to a whole generation of drivers. And gas-car habits are hard to break.

A History Lesson

The 2012 Fisker Karma was a genuine EREV, with about 2,000 sold before that version of Fisker collapsed into bankruptcy. The low, sleek four-door sedan was rated at 33 miles of electric range, after which a 2.0-liter inline-4 kicked on to power it another 207 miles.

End Of Production For BMW i3

A different EREV reached far higher volumes. Like future Scout and Ram trucks, the 2014 BMW i3 offered its REx range-extending engine as an option. But the onboard gas tank was limited to 1.9 gallons, and set the REx to kick in only at very low battery charge. Gas added a mere 78 miles of range, on top of the battery-electric’s 72 miles of range. 

Those low ranges made driving an i3 REx on gasoline alone almost impossible. Owners had to stop and refuel the 39-mpg REx every hour or so. While early REx owners like Tom Moloughney got good at 2-minute fuel stops to add gasoline on road trips, only EV zealots put up with that. 

Thankfully range extenders in new EREVs will likely fire up at a much higher battery state of charge—15% to 25%, perhaps. Like many specs for the future EREVs, we don’t know, and the makers aren’t telling us. 

Whether they’ll tell us anything about when, how often, and even whether they’re plugged in to recharge remains unknown as well. Based on what we know to date, it seems hard not be skeptical.

Photo by: Scout Motors

Scout Traveler Electric SUV

There’s a simple solution to that: The more aggressive emissions regulators in our country (lookin’ at you, California Air Resources Board) can require that EREV makers provide data on how much and how often they’re plugged in—specifically how many of their miles are covered via grid electricity vs burning gasoline.

Whether that has a chance of happening in our current political climate is a different question.

John Voelcker covers advanced auto technologies and energy policy as a reporter and analyst, specializing in electric vehicles and the energy ecosystem around them. He edited Green Car Reports for nine years, and his work has appeared in Car and Driver, The Drive, Forbes Wheels, Wired, Popular Science and NPR’s “All Things Considered.”