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.

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.