Engineers and experts come up with regulation spec, politicians merely enact it. If your toilet design requires dropping a ton of water from one foot, it will naturally not work without one ton of water. However if the manufacturer would turn on their brain however, they could easily come up with efficient jet design that requires less than 1% of previously needed fuel. Market can't adapt in many cases, like plastic bags, subprime mortgage, dogs with bank accounts, Windows and Internet Explorer bundles, and on and on and on. You can have cars with 1.5x better fuel consumption, but 1500x worse emissions. They'll call it "clean emissions".