OK,, there are about 300 guys calling greyhound right now and adding up distances and travel times to figure out what is 42 hours from you....
42 hours to GET BACK... that would be incentive to " overlook" some puffery by the owner.... LOL
I have a 240d with straight body,manual trans, manual windows and no sunroof... so I understand that that is one of the few cars in the world which would warrant such a trip.
Just pick out some good reading material.... and a digital camera to take with you...
After you get there and secure it... do what some of the guys have done about posting your return route ... in case you need some help or just want to have coffee with people on the board.
Then , as you progress, just stop into a library once a day and give a position report....