Congrats to your daughter. Enjoy these years, before you know it they will be graduating from high school. It goes way too fast.
I think if your W brings up car again, explain to her about the safety issues that you mentioned before. I believe it will make her think and realize getting the car was not at all about her!
As for the teenager I don't think it will make anything worse or better. She is in a fog and probably doesn't listen to anyone who tells her she is wrong. I think it just irritates them badly,ha!
Life's challenges are not supposed to paralyze you, they're supposed to help you discover who you are. -- Bernice Johnson Reagon