If people won’t trade their cars in for bicycles, they can still be environmentally friendly by driving in groups the way cyclists do.  In your car, it’s called tailgating, and it’s a terrible idea.  But cyclists call it drafting, tucking in right behind another bicycle to cut wind resistance and therefore energy output, and that’s a great idea.  And an article in the new issue of the International Journal of the Environment and Pollution theorizes that an automated system that would let cars travel in very tight groups would indeed save fuel, cut greenhouse gas emissions and also cut highway congestion.  Especially with fast-developing countries like China and India becoming home to huge numbers of new cars and roads.   

Obviously, driving in tight packs of cars isn’t currently a sensible option.  But large distances between millions of more cars in the future may also not be a sensible option.  And automated systems that would let a driver pull within a few feet of another car would have an additional benefit to both passengers and the environment—less road noise, which is another real drag.