Hate to say it, but she broke the contract. However, from the sound of the OP, you didn't say it'd be gone for good, just taken away, right?
I have no idea how it is with her and her mother but there could just be trouble at home there, but 16 years old is that age when practically every girl snaps back. It's nothing new, don't hold that against her, that's a different issue altogether that needs to be worked out in my opinion. The Jeep has to do with the contract, not her attitude with the mother.
In my opinion, she should at least get the chance to get it back. Whether or not you want her to pay a few more or not along with the grades coming up as a penalty is up to you. She doesn't know how high the bar can go, so give her the attitude of, "I know you can do better" rather than settling with this.
I have no idea how it is with her and her mother but there could just be trouble at home there, but 16 years old is that age when practically every girl snaps back. It's nothing new, don't hold that against her, that's a different issue altogether that needs to be worked out in my opinion. The Jeep has to do with the contract, not her attitude with the mother.
In my opinion, she should at least get the chance to get it back. Whether or not you want her to pay a few more or not along with the grades coming up as a penalty is up to you. She doesn't know how high the bar can go, so give her the attitude of, "I know you can do better" rather than settling with this.