I have had, and continue to have the same problem. I don’t drink, 2 of my friends do. So it falls to me to be the taxi home as I’m going their way!!
They have, at the beginning, suggested I leave the car, have a wee drink, and share a taxi home with them. But I rarely drink, get very tipsy on one drink, and prefer the convenience of leaving when it suits me and not waiting forever on taxis.
And that is my bug bear.... I don’t have the freedom to choose when I turn up or leave because I’m the taxi!!
They also offered me petrol money, which I don’t want/need.
I have lied, saying I’ll meet them later as I have a previous engagement and they have either not gone to the event or bemoaned the fact that they’ll need to get a taxi!!!
I have also told them before events, that I’ve had a long day/week and would be leaving event early etc
To which they reply. ‘Oh just as we were enjoying ourselves’!
It makes me both furious at their audacity and at myself for feeling guilty of ruining their nights.
I can’t see a way out of this, without stubbornly declining lifts when I’m going to the events anyway
Or
Just not going.
So I put up & shut up
I’m on Nitrofurantoin and feeling so sick.
Ha! Ha! Haaaaaaaaa! An OBE in exchange for the State Pension?
. 7th time of trying! She had a car and within a year drove up to see me at university, from London to Sheffield. She was a determind woman and still driving in her 80s, but v..e..r..y slowly. She got Alzheimers and stayed at home but claimed she still drove 
