Cars are awful investments. For people in the military it's even worse. You may be gone for 12-15 months at a time on deployment, and it's depreciating in value weather it's being driven or not.
I wouldn't buy a new car if I was in the military. I would buy a beater for when I'm state side, and put the money that would be going in to a loan in a
high yield savings account separate from the normal savings and checking account. Then I'd be collecting interest not paying it.
A friend of mine did this, then after his final deployment he paid cash for new $30k+ truck.