Here’s how the EPA calculates how far an EV can go on a full charge

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How does the US Environmental Protection Agency decide how far an electric vehicle can go on a single charge? The simple explanation is that an EV is driven until the battery runs flat, providing the number that goes on the window sticker. In practice, it's a lot more complicated than that, with varying test cycles, real-world simulations, and more variables than a book of Mad Libs, all in an effort to give you a number that you can count on to be consistent and comparable with other vehicles on the road.

The start of EPA mileage testing

The EPA started testing vehicle fuel economy in 1971, and that initial testing still plays a major role in how modern cars are measured.

The year before, President Richard Nixon signed the National Environmental Policy Act of 1969 (followed by the Clean Air Act of 1970) and established the EPA with a mandate that included lowering motor vehicle emissions. Part of the EPA's plan to reduce emissions was to let buyers know just how much fuel a car would use so they could cross-shop cars effectively.