Dear EarthTalk:

Is it greener to keep an old car running as long as possible or replace it with a newer, more efficient or electric model?

Richard M., Portland, ME

Drivers who care about the planet often face a tricky choice. Should they keep driving their older gas-powered cars until they completely break down, or trade them in early for an electric vehicle (EV)?

For a long time, the traditional argument was that drivers should hold onto their old cars for as long as possible. The main idea was that manufacturing a brand-new vehicle creates a large amount of pollution and carbon emissions right away, so building fewer cars is better for the environment.

However, new scientific research challenges this common belief. It shows that burning gasoline every day causes much more damage over time than the initial cost of a new car. As Dr. Elliott Campbell, an environmental studies professor at UC Santa Cruz, points out: “An EV has a [half] ton battery but a gas vehicle can use 20 tons of petroleum in its life... once you burn petroleum it's essentially gone forever.”

Because gas cars burn through so much fuel, even replacing a car that is only a year or two old with an EV can reduce overall greenhouse gases within a surprisingly short amount of time. This brings up the concept of the "carbon payback period." This is the time it takes for an EV's clean driving to wipe out the factory emissions caused by making its battery and metal frame. Recent studies show that this payback period usually takes only about three years. After that point, the electric vehicle provides a massive net benefit for the planet compared to keeping a gas guzzler on the road.

When you compare the lifetime emissions of burning fuel in a standard engine versus powering an EV with a modern, increasingly clean electricity grid, the benefits grow even more. According to Dr. Campbell, “The environmental advantage of EVs is now crystal clear.” Climate writer Curtis Deacon notes that “Their modeling found that, for most drivers, making the switch earlier can reduce emissions. That means retiring a still-functional gas vehicle and replacing it with an EV may provide a meaningful climate benefit.”

Of course, there are exceptions to every rule. If someone rarely drives at all, keeping their old vehicle might still make sense because manufacturing emissions take much longer to pay back if the car sits in a driveway most days. We also have to consider the broader material advantages of EVs. Heavy metal components and batteries can be recycled and reused, unlike burnt fossil fuels that vanish into the atmosphere forever as greenhouse gases.

Ultimately, holding onto an aging gas car just to save the planet is often a myth. Trading up to an electric vehicle sooner rather than later is usually the much greener choice for our future.

CONTACTS

• New Science Says Scrapping a Working Gas Car For an EV is Usually Greener, .

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