How the EPA determines electric vehicle range

Since the Environmental Protection Agency was founded in 1970, one of its primary tasks has been testing gas burning vehicles - both to see how much they pollute and to tell consumers how many miles per gallon they are liable to get in a car. But since electric vehicles came to market in significant numbers after 2010, the agency has begun shifting toward testing EV range. The trouble is that EV technology is changing…fast. The agency has had decades to refine standards for gas burning cars, and just a few years for EVs. Some critics say the tests are inaccurate. CNBC went inside the EPA's testing lab to find out how they test for EV range.