This is one case where the context, as well as the intonation and attitude of the speaker, can possibly give you more information than the actual words!
Originally Posted by hiroff
I agree that the words themselves are not rhetorical, and it is a perfectly acceptable question.
However, I have also known many people who add phrases such as "or are you driving yourself?" to make a separate point, some examples being:
- I'm being nice to offer, but I'd really prefer that you drive yourself
- we're having an argument and maybe you'd rather not be with me right now
- I don't think you should drive, but I don't want to insult you with my offer
This is the cultural part of learning a new language that is SO hard to learn and explain! All languages have things like this - it just takes a lot of experience with native speakers to understand, I'm afraid. Good luck, and have fun!