I used to get a ride to an out of city campus, from a girl in my class everyday, way back when lol:P I didn't drive. I paid her and when the semester was over I bought her a nice gift. I cannot imagine someone not doing this for you.
You sound kind-hearted, good for you and shame on them for taking advantage, my goodness she can drive!!!
If I were you...this is what i would do. Of course what you decide it entirely up to you. I would talk to her.
Tell her look I drove you as a "favour" a few times. (Which you did , which was nice and I would let that go as far as reimbursement of some sort) but then ASK (in order to set the record straight/set guidelines whatever you wish to call it.) Will you require a ride for the rest of the semester? If she says yes. Then tell her we both have cars you know how expensive gas is, I can't afford to pay for the extra time out of my way, then ask for money or the equivalent in coffee cards what have you.
If she says yes.
You have now set up a verbal agreement and if it is breached you have every right to bring it up and say, we discussed this and you need to pay me before we leave school or whatever the set up was or I can't keep driving you.
If she says no, then you aren't driving her anyway:)))
It can totally be done nicely, I imagine you would be super nice about it anyway. But set the groundwork to make sure she knows, you are happy to help BUT not a free taxi.
