Is it Environmentally Friendly Living in an RV?

When you hear someone state “I live in a vehicle that gets 7mpg”, do questions of how environmentally friendly the full-time RVing lifestyle can be come to mind? There are a plethora of ways to travel this world. Vandwelling, RV living, hotels, backpacking. Some are easier on Mother Nature than others, but I want to specifically address how living in vehicles as your home impacts the earth.