I've got a friend who was learning to drive a car at some point but she never finished.
Could she say: "I was learning to drive but never finished?" - does it sound natural; is it grammatically correct?
And would the next sentence have the same meaning? "I studied driving but never finished".
Thanks in advance, after learning English for a long time I still can't figure out some nuances.
Both sentences you have written are grammatically correct (except there is no need for '?' at the end of the first sentence).
The first sentence is natural, and a common way to talk about something like that.
The second sentence is unnatural. We don't study driving to become a driver. We learn the actions of how to drive. If we said: "I learned to drive but didn't finish", this is incorrect. That's why the past continuous is better to use in this context, and when talking about things that you were doing but didn't finish.