calculate the cost of getting to/from the airport into their holiday budget?
I know I may be offered petrol money but I don't want to spend two consecutive sundays on an airport run.
Just pay for parking or get a taxi or train. I mean you're willing to pay airfare to get to your destination so why is the distance between your home and the airport not part of you holiday journey?
(I know I could have declined and for anyone else I would have made up excuses but am trying to see the bigger picture about previous favours this person has done for us. It just reminded me that this is a bug bear of mine)