I don't drink so much nowadays and when I do it's rarely enough to be impaired/illegal for driving (in which case I wouldn't have the car, obviously) so I tend to be taxiing people all over the place.

That said, there are times when I draw the line. Like last week when a friend asked if I'll come out and drive into town especially just to pick him up, and drive him to the pub near me. At which point I politely told him to smurf off as there's a bus literally a 2 minute walk away due in 10 minutes that stops outside exactly where he needs to be

Sure it'd save him money for the bus but
a) He's well paid (better than me now, far as I know)
b) Oh sure I'll just spend about £1 on fuel plus general wear and tear just to save you paying for a bus ticket!

I'll do things for friends but am not a doormat (or possibly am a terrible friend *shrug* we laughed it off though)