Drove back to DH's home town (about 100 miles away) this weekend for a family party. The relatives we were visiting live a few miles out of that town, with no public transport, so we hired a car. DH asked SIL, who doesn't drive, if she'd like to come in the car with us, as she lives nearby. Now, if I was SIL and was getting a door-to-door lift (we picked her up and dropped her off), which saved me a train fare of almost £50 (just to get anywhere near to relatives' house), I would definitely offer some money towards the petrol. Am I being unreasonable to expect that she would have done so?