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‘What’s the best kind of car for the climate?’ » Yale Climate Connections


ASK SARA

'What's the best kind of car for the climate?'

Hybrids and electric cars can offer significant benefits.

Electric car

Dear Sara,

I live in a city that does not have great transportation options, and I live far enough from my work that I am not able to walk or ride a bike. I have a 15-year-old car that I am looking to replace. My husband and I are open to buying a hybrid or electric car. We live in Michigan, and the gentleman at the dealership told us that in our climate, we would not get maximum efficiency out of a hybrid due to cold temperatures in the winter. Additionally, I understand that hybrid and electric cars have less of a footprint on the road, but require greater resources to create, thus negating the benefit. Is that true? – Christina in Michigan

Dear Christina,

One of the claims you’ve heard is true – but it’s not the whole picture. And the other is false. As I’ll explain, Michigan is an imperfect place to drive hybrid or electric vehicles. But overall, their benefits to the climate outweigh the drawbacks, so these vehicles can make solid choices even in your cold Midwestern state.

Why hybrids can be better for the climate

Most cars and trucks run by burning diesel or gasoline in internal combustion engines. They contribute to climate change by releasing heat-trapping carbon dioxide from their tailpipes.

Hybrid vehicles, by contrast, contain both an electric motor and an internal combustion engine. The electric motor assists the gasoline engine and in some cases propels the car on its own, boosting the vehicle’s efficiency. Hybrids also take advantage of several fuel-saving features, such as powering off automatically at stoplights to prevent idling. As a result, they typically boast better fuel economy – and therefore a smaller climate impact – than vehicles running on conventional engines alone.

But be sure to compare mileage ratings: A hybrid SUV may get fewer miles to the gallon than a compact car running on a conventional engine alone.

The climate benefits of electric cars

Fueling and driving an electric vehicle generally produces far less carbon dioxide than a car with a conventional engine. That’s because across much of the U.S., generating the electricity to charge the car produces less heat-trapping pollution than burning gasoline or diesel.

That said, the mix of fuels powering the electricity grid makes a big difference to the climate impact. For example, California generates less than half of its electricity from fossil fuels. As a result, the average electric car charged in the Golden State is responsible for the same amount of carbon dioxide as a gasoline car getting 109 miles per gallon, according to a Union of Concerned Scientists analysis. In Michigan’s Lower Peninsula – where a larger share of electricity is generated from fossil fuels – an average electric car pollutes as much as a gasoline car getting 49 mpg. That’s worse for the climate than an electric car fueled in California, but still better than the average new car with an internal combustion engine.

In fact, most U.S. residents now live in a place where electric cars get at least the equivalent of 46 mpg, and often much higher. You can see the mileage estimate for your region here.

When it comes to climate change, an electric car holds another advantage over vehicles with conventional engines: the opportunity to improve if and when the grid reduces its reliance on fossil fuels.

“If you buy a gasoline car, you know, the efficiency is set,” said David Reichmuth, an engineer who studies vehicles at the Union of Concerned Scientists. “If anything, it gets a little less efficient, you know, as the car gets older – whereas the electric car could effectively become cleaner over time, not because it becomes more efficient, but because the electricity going into it will become cleaner over time.”

How does cold weather affect vehicle efficiency?

Your dealer was correct to say that cold weather reduces the efficiency of hybrid vehicles. But that’s not the whole picture. In fact, cold weather causes efficiency to decline in all three kinds of vehicles – hybrid, electric, and internal combustion engine. In icy temperatures, vehicle batteries and engines simply don’t perform as well as they do in warmer weather, among other factors that drag down efficiency.

According to FuelEconomy.gov, a gasoline car’s mileage is 12-22% lower at 20 degrees Fahrenheit than at 77 degrees. For hybrids, fuel economy falls by 31-34% in cold weather.

But that need not deter you from purchasing a hybrid vehicle – provided you choose one with a high mileage rating. Top-performing hybrids, such as the 2019 Hyundai Ioniq hybrid (58 mpg) and the 2019 Toyota Prius (56 mpg), will likely contribute less to climate change than vehicles with conventional engines, even accounting for cold-weather efficiency declines.

As for electric vehicles, a 2015 paper by Carnegie Mellon researchers found that the range of the Nissan Leaf can drop by as much as 36% in cold climates. Test drives of several electric vehicle models by AAA and Consumer Reports have also found substantial range losses in cold temperatures. So don’t miss these tips from Consumer Reports, which advises those living in cold climates to purchase a car with twice the range they expect to use.

But despite Michigan’s cold climate, the Carnegie Mellon researchers found that an electric vehicle will still likely pollute less than one with a conventional engine. Taking into account the carbon impact of the regional electricity grid and the diminished performance of electric vehicles in a cold climate, the researchers calculated that a Nissan Leaf driven in Michigan’s Lower Peninsula is responsible for roughly 200 grams of carbon dioxide per mile driven. That’s about half as much as the average new vehicle, according to this greenhouse gas emissions calculator from the U.S. Department of Energy and the Environmental Protection Agency.

How manufacturing affects the climate impact of hybrid and electric vehicles

Christina, you’ve heard that hybrid and electric vehicles consume more resources to manufacture than vehicles with internal combustion engines. It’s true that producing hybrid and electric vehicles requires more energy – and associated greenhouse gases – than those with only internal combustion engines. Manufacturing batteries for electric vehicles, in particular, consumes a lot of energy.

However, that does not negate the climate benefits of the vehicles. Calculating the lifetime impact of the vehicles is complex, but various studies suggest that after they hit the road, hybrid and electric vehicles more than make up for their energy-intensive beginnings.

Reichmuth of the Union of Concerned Scientists, an author of one such analysis, said that excess emissions from manufacturing electric vehicles are offset quickly: “As long as the car’s driving for more than a couple years, there’d be a net emissions benefit,” he said.

The bottom line: Either a hybrid or electric vehicle is likely a better choice for the climate than a vehicle with an internal combustion engine, even in chilly Michigan. But nothing beats avoiding unneeded car trips in the first place, so don’t neglect to let your leaders know your thoughts on improving local options for walking, biking, and public transit.

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