One truly comfort food that I can think of right now are those cuban sandwiches that 7 Eleven sell. The most important thing though, otherwise its just another bland gas station sandwich, is to have them mash it for you. That's what I like to call it but they have a machine that toasts and mashes the thing until its pefectly melted and the bread crispy. This is a comfort food I learned from my folks. Usually this is something we would and still do before a long drive. For my folks though the whole meal is cubans and a bag of Munchos. I usually don't care for the munchos as they are a little to greasy for me.
Even if there is no long trip sometimes I'll just do it for lunch. Sometimes I'll get two mashed cubans(they are very tasty and sometimes you need two ok), cool ranch Doritos, and of course the most important ingredient to the whole meal, Dr. Pepper(Usually the super big gulp).
But I'm telling you, the sandwiches are tasty, warm and a soothing type of food.