It doesn't even have to be a beater. For $2,500 one can buy a car with several years and tens of thousands of miles left on it. Throw in another thousand for a repair reserve and she is set for several years.
I know this works because this is how I do it. No car payments and liability insurance only - no collision.
I am a 50+ year old software support engineer in Alabama, and for about 8 of the last 10 years I have commuted 25 miles every day in a car (actually cars) with no air conditioning. I can do this because I am committed to cheap transportation.
With the 20 thousand cash left over from selling her new toy she could start a new life, get an education, start a business, etc. For some reason, however, I imagine this is the furthest thought from he mind.
My car is 18 years old, has 186K plus miles. No ac/no heat but gets me to the grocery store, doctor's appointments, and church. Runs pretty darn good too for such a "beater".