Not required but if you're friends, kind of. I think it's odd not to. If you're not close friends, I would like more of an acknowledgement as someone else has said. Because if it is a friend, most likely they'd get me back in other ways or I would also get favors from them. If it's truly on the way, then I probably wouldn't care as much. I don't mind going out of the way a little. If it's a one time thing, no biggie. Today I'm going to drive 25 miles to pick my friend up since her car is broken down again. And then drop her off at some point.