It's always a good idea to keep snacks on hand for those times during the day that you're a little hungry but not ready for a meal. It's also important to have a small snack in order to keep your blood sugar level, deeming it less likely to binge and overeat later.
Trail mix is an easy thing to keep in the car that won't go bad or start creating a foul smell after it's been in there a while.
Having a dip for me is kind of like comfort food. I love to grab some flax crackers and carrot sticks and dip them in hummus or guacamole for a quick, nutritious snack.