I assume from the numbers that your car loan rate is because of your credit score, which is in part due to your credit card debt. That debt, even if at 4%, is probably creating trouble elsewhere (like the car loan). That 4% might be capped, but you don't want decisions about staying in or being a civilian again to be about your interest rates. Clear the debt, refinance the car when you're able, and you'll be in much better shape by 30.