since she brought in that much business. Remind her to focus on her driving and not be distracted by the passengers. These many teens in a moving car can be a very dangerous condition.
But what she really needs to learn here is how to say "No." Or, you can tell her that you cannot allow her to be responsible for the safety of so many others. It's not her responsibility and should not be. If they are her true friends, they should understand, and their parents should understand.
This is a good chance for her to learn to value herself.
If you allow this to continue, you are doing her a terrible disservice, and, forget about the gas money, you are allowing her to be in a dangerous situation.
If there is a time to be a parent, it is now.
