in order to legally 'import' the vehicle it has to go through customs:
10 second google search
You won't be able to permanently import a vehicle your 'buddy drives over' or facilitate a legal registration with a Canadian title ect.
However, regarding him driving it to the border, having the vehicle inspected by CBP for legal import ect, I would imagine there are people that just meet at CBP, get their ducks in a row, have a broker file paperwork and drive away in their vehicle that day.
I picked up my truck at a RORO port and drove it out of there.