A little late getting into this topic but.....
I think at this time, the re-imbursement costs should be monitored weekly. Gas costs has climbed to $3.79 since this topic was posted.
If we drove my Ford Dually today, with diesel at $4.39, my costs just for fuel would be close to $0.30 per mile, not even counting the other vehicle expenese already discussed here.
But then I could carry six people and all their gear in that monster truck.
Personally I'd not care about anything but a split with gas expenses. I'd not even care about wet seats and muddy boots.
Heck... after a few JD's, you could talk me into driving that Dually to the top of Blood Mtn on the AT... LOL
