Well, if it is just her and this boy.... that is a "date" mom. She's pulling wool over your eyes if you believe differently. If you have a rule of no one on one dates until she is 16 and she is not 16, then she doesn't go. Period.
Secondly, Most 15yr olds have a permit by now and are preparing for their license. When a license is obtained in TX, it is like a graduated license. NO car can be full of teens with a teen driving. They can and will be ticketed,,, at least they are in my area.
The exception is a family member in the car.
Other than that, I believe 1 other person can be in the car that is under 18 and that is it. They have to renew the license EACH year until they turn 18 and then at 21 they get the 21 license.
Having rules is one thing but if you don't enforce them, it means nothing.
At the same time, you have to let the purse strings go a bit because teens can't learn to be responsible and independent if they are kept under a rock or in bubble wrap all their lives. True, tragic things happen and it is tragic, however, something tragic has just as much of a chance happening on your watch as well.
My daughter is 20 now. She did ride with others occasionally per state rules. She drove herself to school (20 minutes from our home) daily 1-2 times depending on schedule. So a 25 minute drive from my house is nothing, it is just across town.
As someone else mentioned... the most sheltered and over protected teens are the ones who end up in trouble at college most of the time because it is their first taste of freedom.