I would strongly advise you not to lend her the money..

It is great risk for which you will be exposed for a long time until the monthly installment ends..you cannot predict what will happen..

- imagine if she got terminated for whatever reason?
- imagine if she did not pay for a month or two because of other commitments.
- imagine if she goes for vacation and never return which is common.

you have to remember that having a car is not a matter of life or death so it can wait.

if I have a good a friend asking me for the same I would say no, and if he is truely a good friend he would understand.

Choice is yours