Is this only for new vehicles
Pre-approved checks? NO -- You can buy used.
My partner had one for 2 months... we never used it (ended up leasing new Kia) and Navy sent a letter stating they voided the check because we didn't use it but rest assured if we had used it, they would still honor it and if we wanted it agian, just call them and they could most certainly probably issue another loan.
you can apply blank and they will approve for as much as possible or you can request the amount you want.
Thank you I am just not sure if I want to buy a new car I am still deciding but thank you for the information