What a range extended electric vehicle is

A range extended electric vehicle (REEV) is a car that runs on a battery most of the time but has a small gas engine inside that kicks in when the battery gets low. The gas engine does not turn the wheels directly — instead, it powers a generator that charges the battery while you drive. This is different from a hybrid, where the gas engine sometimes powers the wheels on its own.

The battery in a REEV is smaller than in a fully electric vehicle, which makes the car cheaper and lighter. You still plug it in at home or at a charger, just like an electric car. Most days, if your commute is short enough, you may never use the gas engine at all. The gas engine is there as a backup so you do not get stranded if you drive farther than the battery can take you.

The Chevrolet Volt is the most common REEV sold in the United States. It has a battery range of about 40 to 50 miles on electricity alone, and when the gas engine turns on, it can go another 300 or so miles before you need to refuel. Other manufacturers have offered range extended models in different markets, though availability changes year to year.

Key Takeaways

  • A REEV runs on battery power for daily driving and uses a gas engine to generate electricity only when the battery is nearly empty, so you can drive longer distances without stopping to charge.
  • The gas engine in a REEV does not power the wheels — it only charges the battery, which is why the car stays efficient even when the engine is running.
  • REEVs are cheaper than fully electric vehicles because the battery is smaller, and they do not require the charging infrastructure that pure electric cars depend on for long trips.
  • If you drive less than 40 to 50 miles most days and have a place to plug in at home, a REEV can run almost entirely on electricity, cutting your gas use and emissions significantly.
  • REEVs produce fewer emissions than gas-only cars but more than fully electric vehicles, because the gas engine still burns fuel on longer drives.

How the battery and gas engine work together

When you start a REEV, the battery powers the electric motor. As you drive, the battery drains. Once the battery reaches a set level — usually around 20 to 30 percent — the gas engine starts automatically. At that point, the engine runs a generator that produces electricity to keep the battery charged while you continue driving.

You do not feel a big jolt when this happens. The transition is smooth because the electric motor is always doing the work of moving the car. The gas engine straightforward maintains the battery level instead of letting it drop to zero. This means the gas engine never has to work at full power the way it does in a regular car, so it runs more efficiently and produces fewer emissions per mile.

When you brake, the electric motor captures energy and feeds it back into the battery — a process called regenerative braking. This happens whether the gas engine is running or not, so you recover some energy every time you slow down. Over a full drive cycle, regenerative braking can add 10 to 20 percent more range, depending on how much city driving you do.

Daily driving costs compared to gas and electric cars

If you drive 40 miles a day and charge at home overnight, a REEV will use almost no gas. Electricity costs roughly one-third to one-half as much as gasoline per mile, so your fuel cost drops significantly. You pay for the electricity to charge the battery, which might be $3 to $5 per night depending on your local rates and how depleted the battery is.

A fully electric vehicle would cost even less per mile to run, but it requires either a home charger or access to public charging stations on longer trips. A REEV does not have that constraint — the gas engine means you can drive 300+ miles without planning around charger locations. For someone who drives mostly short distances but occasionally takes longer road trips, a REEV can eliminate the anxiety of range without the cost of a larger battery.

Compared to a gas-only car, a REEV owner who drives 12,000 miles per year and uses the gas engine for only 30 percent of those miles might spend $400 to $600 less on fuel annually, depending on local gas and electricity prices. The savings grow if you drive more miles on battery power.

Environmental impact of range extended vehicles

A REEV produces fewer emissions than a gas-only car because most of your driving happens on electricity. If your electricity comes from renewable sources like wind or solar, the emissions drop even further. If your grid relies more on fossil fuels, the emissions benefit is smaller but still real — power plants are more efficient at burning fuel than car engines are.

Over a year, a REEV owner who drives 12,000 miles and uses the gas engine for 30 percent of those miles will produce roughly 40 to 50 percent fewer emissions than someone driving the same distance in a gas-only car. The exact number depends on your local electricity grid and how much you actually use the gas engine.

A fully electric vehicle produces zero tailpipe emissions, so it is cleaner than a REEV if you have reliable access to charging. However, a REEV produces fewer emissions than a hybrid or a gas car, and it does not require the mining and manufacturing of a very large battery. For someone who cannot install a home charger or who takes frequent long trips, a REEV may be a more practical way to cut emissions than waiting for a fully electric option.

When a REEV makes sense for your situation

A REEV works best if you have a predictable daily commute of 40 miles or less and a place to plug in at home or at work. If that describes your routine, you will run on electricity most days and use the gas engine only occasionally. The car pays for itself through fuel savings over time, and you get the environmental benefit of electric driving without the range anxiety.

A REEV is less ideal if you drive more than 100 miles most days, because the gas engine will run frequently and you lose the efficiency advantage. In that case, a gas-only car or a fully electric vehicle with a larger battery might make more sense. Similarly, if you have no place to plug in regularly, the battery will stay small and the gas engine will run often, which defeats the purpose of having a REEV.

REEVs also make sense if you live in an area with limited public charging infrastructure but want to cut your gas use. The gas engine is your safety net, so you do not have to worry about finding a charger on a longer drive. This is especially valuable in rural areas or regions where charging networks are still developing.

Maintenance and reliability of range extended vehicles

A REEV has both an electric motor and a gas engine, so there are more parts than in a fully electric car. However, the gas engine runs less often and at lower stress than in a regular car, which can extend its life. The battery is smaller than in a pure electric vehicle, so replacement costs are lower if the battery eventually needs service.

Routine maintenance includes oil changes for the gas engine, though they happen less frequently because the engine does not run as much. Brake service is lighter than in gas cars because regenerative braking does most of the stopping. Tire wear is similar to any other car. Overall, maintenance costs for a REEV typically fall between those of a fully electric vehicle and a gas-only car.

REEVs have been on the road for over a decade, and real-world reliability data shows they are dependable. The Chevrolet Volt, for example, has a strong track record for durability. Because the gas engine is a backup system rather than the primary power source, failures in either system do not necessarily leave you stranded — you can limp home on battery power or use the gas engine to reach a charger or service center.

Cost of buying a range extended vehicle

A new REEV typically costs $5,000 to $10,000 more than a comparable gas-only car, but less than a fully electric vehicle with a larger battery. The Chevrolet Volt, for example, starts around $27,000 to $30,000 depending on trim level and current incentives. A comparable gas sedan might cost $20,000 to $23,000, while a fully electric car with similar range would cost $35,000 to $45,000 or more.

Some states and the federal government offer tax credits or rebates for REEV purchases, though the amount and availability vary by location and change over time. Check your state's environmental agency or energy office website to see what incentives are currently available in your area. These credits can reduce the upfront cost significantly, sometimes bringing a REEV closer to the price of a gas car.

Used REEVs are increasingly available as early models age out of leases. A used REEV can be a cost-effective way to try the technology without paying the full new-car price. Battery health is the main concern with used models, so ask for a battery report or have a dealer inspect it before you buy.

Frequently Asked Questions

Can I drive a REEV on just the gas engine without charging?

Technically yes, but that defeats the purpose. If you never charge the battery, the gas engine will run constantly and you will get worse fuel economy than a regular car. A REEV only makes financial and environmental sense if you charge regularly and use the battery for most of your daily driving.

How long does it take to charge a REEV at home?

A standard 120-volt outlet takes 8 to 12 hours to fully charge a REEV battery. A 240-volt home charger (the same type used for electric cars) charges the battery in 2 to 4 hours. Most owners charge overnight, so the car is ready for the next day's commute.

What happens if the gas engine fails in a REEV?

The car will still run on battery power alone, just like a fully electric vehicle. You can drive to a service center or charging station on battery power. The gas engine is a backup system, not the primary one, so its failure does not leave you stranded the way an engine failure would in a gas car.

Is a REEV better for the environment than a hybrid?

Yes, generally. A REEV runs on electricity for most daily driving and uses the gas engine only as a backup. A hybrid uses the gas engine regularly and cannot be plugged in, so it produces more emissions. If you drive short distances and charge daily, a REEV will be significantly cleaner than a hybrid.

Can I take a REEV on a long road trip?

Yes. Once the battery is depleted, the gas engine turns on and you can drive another 300+ miles before refueling. You do not need to plan around charging stations the way you would in a fully electric car. The trade-off is that fuel economy on a long trip will be lower than on a short daily commute.