Not sure how it relates to expeditioning but it is worth considering, if it's compatible.
IMIEV Mobile Power Source
Now, I don't know how compatible it would be as I have no experience of hybrid vehicles and their systems. Considering it plugs into the charging outlet for the car I would assume that those points have a greater throughput of power.
I would also hope that those are not all-electric cars they are pulling the power from because if so someone seems to think that the electric cars generate their own power with a combustion engine... Nah, they wouldn't be that daft, right?
Thanks to Ernie on the MH list for that link