Your assuming mile wide lanes. Lets assume 2 lane roads. Normal 12' wide lanes means 48' of width.
5280'long X 48' wide = 253,440sq feet per mile
253,440sqfeet per mile X $43 = $10,897,920 per mile
$10,897,920 per mile X 25,000 miles =
$272,448,000,000.
So $273 billion or so for nationwide energy independence would be pretty cheap if you ask me.
I cant keep my kids eyeglasses from getting scratched up every six months, so im not sure how they will keep the clear covering scratch free...if they cant then that efficiency goes way down I bet.