What is a low calorie breakfest one can eat while traveling?

I just started a job where I travel around PA and NY alot, and I was wondering what my options were for eating a filling but low-calorie breakfest? Obviously I can't store milk in my car for cereal, and most places like fast food are to fatty. Restaurants like Friendlys, Dennys, etc take a long time to sit down, order food, wait on service, that it takes a lot of time out of my day. Is there any fast, low calorie options I have left? And don't say breakfest bars because I could eat 30 of those and still be hungry.