In the archives, the latest one has to go with splitting cost of a trip, as far as gas and wear and tear on the car.
Other reasonable people may have different opinions, but mine is, since the trip was already taken and is over, and no advance agreement was made, the car owner should settle for half the gas. Naming a higher price after the fact can really create problems.
Other than that, I agree with the brothers on other options, if the agreement is made in advance.
Yes, now that the trip’s done, half the gas is the only ‘fair’ (a four-letter word in negotiations) way to go. They did a good job summarizing most of the options. It can range anywhere from buddy pays driver big $$ (if driver wasn’t going) to driver pays buddy something (if driver wanted company). But all that has to be set up front.