If I make the slightest indications that I don't feel like it, it hurts her feelings. She isn't a "rage" type, she just gets quiet and and sad and gives up and makes me feel guilty.
So she gets you to enable her to not learn to drive. It's okay for her to be upset. This is a hard lesson. We feel we need to protect our loved ones from feeling hurt or upset, but if the cause of their being upset is we enforce a boundary, then
you do not have to feel bad about it. This is hard and takes practice.
If you want to set a boundary of only driving her places when it is convenient for you, or only when you are not tired/sick.busy, that is okay. And setting a boundary is not about proclaiming it to the pwBPD. It's about picking something you will not allow anymore, and then standing by it. After some time, the pwBPD gets used to the "new normal" and acclimates. There will be cranky times over it. Ignore accusations based on irrational requests. It is not rational to expect you to play chauffeur all the time. It's rude. It's selfish. But if you keep doing it, it won't stop. SHE'S not going to stop it. YOU have to.
Yes, I feel like a caretaker sometimes. And that's a hard place to be when you want an equal adult level relationship instead of a child/parent/patient/caretaker feeling. But we have to step back and see what we do that allows things to continue, and change ourselves. We can only change our own actions. So see if you can step back from the driving so much. Don't make a big deal out of it. Be busy. Be absent. Make her learn to rely on herself to get from A to B. It's another step like self-soothing. If you are always there to do it, she will never HAVE to learn otherwise.
I've had to step back and let H fail at some things so he'd learn to do them. It did teach him a little more self-reliance, and made him motivated to get past some hurdles he'd built for himself. He fixates on negative things, he make excuses all the time for not doing what he knows he should. I can't stand being a nag, so I just do thigns that bother me if they are not done, and ignore what I can't do, and let him complain if that's the case. He seems to be learning that he has little right to complain about some things when he knows it's because HE won't step up and do them.