Is a plug-in hybrid better than a fully electric vehicle?

Climate Lab is a Seattle Times initiative that explores the effects of climate change in the Pacific Northwest and beyond. The project is funded in part by The Bullitt Foundation, Mike and Becky Hughes, University of Washington and Walker Family Foundation, and its fiscal sponsor is the Seattle Foundation.

Like most things, the answer to whether one car is better than another depends on what you’re looking for.

That’s probably disappointing to hear. So it goes. This isn’t a cut-and-dry issue.

What’s the problem in the first place, you might ask? Internal combustion engines. You put in gasoline (or diesel), the fuel combusts, pushing pistons back and forth, and voilà, we’ve got a moving vehicle.

Combusting fossil fuels also churns out greenhouse gas emissions, warms the atmosphere and exacerbates climate change.

That, in a nutshell, is the problem. So, how do we reduce (or eliminate) these greenhouse gasses while still producing that motion that, ya know, gets us from home to work, to day care, to the grocery store, to our next adventure?

It’s an increasingly pertinent question, since the sale of hybrids, plug-in hybrids and battery-operated vehicles continues to climb. Those three options made up more than 16% of all vehicles sold last year, up from less than 13% in 2022, according to the U.S. Energy Information Administration. Of the three, plug-ins saw the biggest jump, Bloomberg reported, with an 83% increase in sales, compared to 21% with fully electric vehicles.

What are hybrids, plug-ins and electric vehicles? 

A hybrid vehicle operates on both gas and a battery. The battery, of course, relies on electricity so there’s none of that pesky combustion when it’s in use. These vehicles rely on gas for the majority of their time in use but capture energy from their momentum to charge a battery within so they can also lean on electricity some of the time, therefore cutting emissions.

A plug-in hybrid uses the same concept except it boasts a larger battery and owners can plug it in. This way, it’s less dependent on gas to generate an electrical charge and can cut emissions even further. 

And a fully electric vehicle — or battery-electric vehicle, some call them — relies entirely on electricity.

That means fewer greenhouse gas emissions, right? Well, yes and no. Again, it depends.

What kind of emissions are we talking about? 

Sorry, but we’ve got to do a little basic math. Hang in there. 

To find the total emissions of a vehicle, we must consider its entire life cycle, said Ashley Nunes, a researcher at Harvard’s Department of Economics. That means combining the emissions churned out by manufacturing the vehicle, transporting it to consumers, manufacturing the fuel, burning the fuel and scrapping the thing when it’s finished. 

Nunes assumes a 180,000-mile life span for a given vehicle and the figures break down like this: 

An internal combustion engine generates about 370 grams of carbon dioxide emissions for every mile driven. That’s 66.6 million grams over the course of 180,000 miles, or 66,600 kilograms, which equals 73.4 tons of emissions over the car’s full life.

A hybrid generates 270 grams of carbon dioxide per mile, roughly 53.6 tons in its life.

A plug-in hybrid generates 230 grams of carbon dioxide per mile, about 45.6 tons in its life.

An EV generates 195 grams of carbon dioxide per mile, about 38.7 tons in its life.

Wait, you say, why aren’t the emissions for EVs lower? Well, building the thing creates emissions in the first place but the resources inside its batteries — like lithium — are also fairly energy-intensive to mine, refine and transform into something usable.

But there’s your first, oversimplified answer. Over a 180,000-mile life of a vehicle, fully electric vehicles will produce fewer greenhouse gas emissions. Plug-in hybrids are next best, then regular hybrids, then internal combustion engines.

What’s the catch? 

We don’t live in a vacuum. Cars don’t always work as intended. And a tweak in the life of a car can have a big influence on the total emissions. 

The base carbon footprint of producing an electric car and its battery, transporting it to consumers and scrapping the vehicle remains the same. So if those cars aren’t driven to the full 180,000 miles, their per-mile carbon dioxide emissions increase. 

“How many electric cars do you see that are 15 years old or 16 years old?” Nunes said.

However, Don MacKenzie, an associate professor of civil and environmental engineering at the University of Washington, expressed optimism that EVs currently on the road can indeed last those 180,000 miles. 

How your electricity is generated matters too. Charging your EV with power generated at a coal plant won’t cut emissions as much as those that use hydropower, wind or solar farms.

There’s another factor, perhaps the most important one: cost.

First, there are the emissions reductions for every dollar spent.

Hybrids might cost $4,000 or $5,000 more than a normal car, he said. Plug-in hybrids cost even more, and fully electric vehicles cost perhaps $15,000 to $20,000 more than normal.

Local, state and federal governments can offer rebates or tax credits but dollars are limited, Nunes said. 

On that per-dollar basis, the hybrid takes the cake.

Cost also translates to accessibility. What good is an EV if it’s unaffordable? 

If we’re talking about cutting the greatest amount of emissions relatively quickly, MacKenzie said, hybrids again probably win. 

“Are we better off having 10 cars that cut their emissions by 100% or 50 cars that cut their emissions by 50%?” MacKenzie said. 

(Hint: It’s the second option)

Don’t overlook compatibility either, MacKenzie said. EVs and plug-in hybrids must be, well, plugged in, and not everybody has access to their own charging station.

Think outside the box

Let’s not pretend like these are our only options, though. 

Transportation accounts for nearly 30% of our greenhouse gas emissions in this country, and there are plenty of ways to cut that number down. We’d be remiss in assuming it’s a one-for-one scenario where a bad car goes out and a good car comes in. 

If an EV produces about half as much carbon dioxide per mile as an internal combustion engine, a full bus could produce less than a fifth as much carbon dioxide as that same traditional engine. 

Trains can offer similar — sometimes even better — savings, a 2022 U.S. Department of Transportation study found. 

That’s not to say we need to immediately flood city streets with buses, MacKenzie said. These transit options must be accessible and practical enough to attract riders.  

“Low emissions per seat-mile plus $5 gets you a cup of coffee,” MacKenzie said. “It means nothing unless there are butts in the seats.”

Ride sharing and carpooling can also help, Nunes said. 

So can electric bicycles (for which rebates are also available), regular bicycles, walking, roller skates, Razor scooters or a friendly equine. You get the idea. 

Anything to avoid that dreaded, single-occupant vehicle clogging the freeway and spewing carbon dioxide into the atmosphere.

There’s no one way to cut our emissions, individually or collectively. It’s going to take a little bit of everything.

Correction: This story was updated on March 21, 2024, to accurately reflect the name of the U.S. Energy Information Administration.