 that when it comes to cars in particular in the United States, since the late 1990s, we have cleaned up about 99% of what comes out of our tailpipe. The problem now in terms of pollution, not global warming, but pollution, is the particulate matter that comes off your brake pads, your brake rotors, and your tires when they wear out. And guess which types of cars do more of that kind of pollution than any other type of car? You guessed it, your electric vehicle. Why? Because they weigh so much.