You guys are naive. Sure, it's possible, but most people don't do this, don't want to do this and will not do this. And of those that DO some of these things, a large subset probably does it in a ineffective way that OP so nicely illustrated in the phone/1 extra km by car example.

No, the solution must be technical while people are allowed to maintain most of the comfort they are used to. Anything else and you will simply not be able to convince people to do so even if that means burning the world down.