Well, it's perfectly normal to get hungry if you have a meal at 6 and try to go without eating until 1. If you had breakfast at 6 am, wouldn't you want another meal before 1 in the afternoon?
If you can't change your schedule to get to bed earlier, just plan for another meal. Around midnight, eat a bowl of oatmeal, a sandwich, some soup (for extra veggies), or whatever else you'd like as a small meal. That probably means eating just a tiny bit less at each of the other meals to "make room" in your calorie allowance, but that shouldn't be a huge problem, especially if you make that last meal the "veggie catch-up meal" to make sure you're getting in your 5-a-day.
And promise yourself that you won't go out after dinner, car or no car. If you want a cup of coffee, make one. Late night coffee runs are a waste of time and money besides bringing in the extra calories. You interrupt your study time, and you probably also end up getting at least 1/2 hour less sleep (which is actually often a reason for college weight gain. Getting enough sleep is just as important to weight control as exercise is.) A good way to do this is to think of something you really want but haven't bought yourself because it's "too expensive" or "you have more important things to spend your money on." Get a nice picture of that item and attach it to a nice little jar or box. Every day that you don't go out for coffee, put the money you would have spent on the coffee (plus a little for gas) into your jar. Before long, you'll realize just how much you were spending on unnecessary convenience store runs, and you'll have an easy way to save some serious cash.