People who purchase fully-electric vehicles do so to save on the tank, but to also improve the air quality. Electric cars do achieve both of those goals, but not in the way people think they do. Electric vehicles still emit CO2 gas, just not the same way that most gasoline-powered vehicles do.
First off, electric vehicles do not emit direct emissions (known as tailpipe emissions). This is what most electric cars are marketed as, and they do achieve this, making them eco-friendly. However, electric vehicles emit well-to wheel emissions, which is how electricity is produced. Most states in the U.S make their electricity by natural gas, but some cities and states make their electricity through nuclear power, coal, geothermal energy, wind power, or even solar power. Well-to wheel emissions are responsible for around 4,500 pounds of CO2 in the air every year. Granted, this is not as bad as gasoline cars with tail piping, but it is still significant. The cleanest sources of energy are solar, wind, and geothermal, but the three of these are either too slow to produce electricity or too expensive. However, the people using solar power to charge their cars do have the cleanest source of getting electricity because it is both renewable and does not emit any gases (because it is light).
Natural gas is still a great option because it produces up to 60% less carbon dioxide than coal. We think that simply purchasing an electric vehicle is doing more than enough for the environment. It is the best-case scenario that everyone gets solar panels and we extinguish emissions, but that is not viable for most people for multiple reasons, the biggest being location. Not everyone gets the best “bang out of their buck” with solar power because some states do not get the most sun due to their climate. Keep in mind that different sources of energy will improve or be discovered to make electricity cleaner than it already is. For now, simply having an electric vehicle is clean enough if that is what you are striving for, but keep in mind that it is not 100% “clean”.