Electric vehicles (EVs) have more in common with smartphones than they do with actual cars. Their batteries use the same chemistry, ounce for ounce, as the device in your bag or pocket. They last a long time, until they don’t. After a few years, that nice phone won’t last as long or work as fast. And when that time comes, mobile carriers will upgrade you to a brand new phone with more features for little or no money.

Buying a new EV works the same way, except you’ll be spending a lot of money if you try to upgrade. While most new cars lose value, many EVs depreciate much faster and start to degrade in performance, sometimes quite significantly. That can make buying a used EV very appealing.

Automakers update their EVs almost every year, unlike conventional vehicles that typically get an upgrade every three or four years. Battery technology improves so quickly that you can often find better range, charging speed, acceleration and technology from one model year to the next, and sometimes at lower prices.

Overnight, older EVs are obsolete on the market. That doesn’t make them bad cars. But because they’re still relatively unpopular—EVs account for less than 1 percent of all U.S. vehicle sales each year—you can score deals you wouldn’t find with regular gas cars.