How should I thank her?

[bobob]

I have to clear first, she and me are not in a relationship.
Second, I think most people can answer me, since I ask the question in a point as a foreigner. (I am from China) It's more or less a culture knowledge help.
Sorry about that this topic is not relative with love. Moderator can delete if you think it's inappropriate.

She is my roommate. She once had money issues and I helped her before, like paying the rent for her or talking to the landlady. She said she might help me with her car as reciprocal like buying things far away. We live in the city and I never ask for help.
Now I got a job and need a driver license. I asked for her help as teaching me to drive and taking me to the road test.
Now we finish the test and I think maybe I should thank her. All I did till now is filled her gas up every time before we drive, and I did not drive too much. And we usually had lunch/dinner/coffee before/after we drove (of course I paid).
She is an artist and doesn't earn a lot. I have a part-time job and I am tight budget. We both live in poor life and usually cook at home.
We celebrated in a diner after I passed the test and I am not sure I still need to thank you in another way. How American do if you are in this situation.. This is a different and new society and country to me.

Tell me if you need more information.
Thanks for your reply and I appreciate your time for reading!

[BackUpOrGetStng]

Sounds like you've done more for her than she's done for you.

[Gribble]

Offer her oral sex.

[boobaa]

Offer her oral sex.

Heh, he might take this seriously... But well, you never know, maybe your advice could work, lol.

[little pingoin]

It sounds like you have been very appreciative so far. If you feel the need to do more, a cute (but small) bouquet of flowers and a thank you card will do nicely.

Do not offer oral sex. =P

[bobob]

Thanks for everybody. I know Gribble you are kidding!
Yes, little pingoin , thank card might work! Thanks

BTW, do I need to tell her the truth that I want her to be my girlfriend even I did not see any clues that she has interest in me.

[Yggdrasil]

We celebrated in a diner after I passed the test and I am not sure I still need to thank you in another way. How American do if you are in this situation.. This is a different and new society and country to me.

You've done more than enough. There's no need to do anything extra.

If you really want to say thank you in a way that she'll can cherish for a long time, just give her a thank you card from Hallmark or so and write something personal on it.