I'm inclined to agree with Craven on this one, the cost of laying down room temperature superconductors on every road would be astronomical by today's methods. And wouldn't you like, have to lay it down all at the same time? Otherwise what the hell would you do when the superconductor highway ran out and you were back to regular tarmac? You'd need some kind of hybrid vehicle that works on both initially maybe?
That sounds like a 7th grade answer. Once we find what a room temperature superconductor is, we will be able to produce it in bulk, like we can with steel today.
You do realise that your comment is itself a childish answer? No? Well, maybe that's the reason you posted it in the first place.
Riddle me this then, what exactly is your plan for deploying 8 million miles of this stuff? Can you produce the quantity needed overnight, or are you relying on some Harry Potter inspired method of alchemy? I tried to throw you a lifeline with the second part of my post, but you seemed to have ignored this in favour of trying to hurl abuse around like a stroppy child. I would take Craven's advise except for maybe the last part, I'm not sure you would want to come back once you realise how immature you have sounded.