My wife and I tend to travel often. Both for short family vacations and traveling to see family members. We don't live in the same areas as our parents so we seem to be on the road frequently.
When I was growing up we would always stop at fast food or a gas station to load up of drinks and snacks whenever we were on the road, even if it was just a hour drive to where we were going. As we started our own family we decided that was way too expensive and impractical.
We now have a little travel cooler that goes with us whenever we travel. Here is a link to the one we have (although we did not pay this much for it): http://goo.gl/xsl0Ox . When heading out on the road some things that are often packed are, but are not limited to...
Soups in Containers (can heat with microwaves at gas stations)
Pre made pasta dishes (can heat with microwaves at gas stations)
Water (in reusable bottle that you can fill at gas stations)
Homemade Iced Tea
Sandwiches (Canned tuna or salmon mixed with avocado are our favorite for the road)
Salsa for chips and salsa
Hummus and Veggies
and many more...
It costs less than $10 to fill that cooler with enough food for a meal and snacks easily and we are not spending money on needless drinks at the gas station.
If on a longer vacation make sure to hit up a grocery store when possible to replenish. When we're traveling we really like finding a Trader Joe's to stock back up on our fruit and veggies. Also, we've had some great luck getting free ice when stopping because we show the cooler to gas station attendants and tell them we'd be wasting a lot of ice if we have to purchase a bag. In the worst of cases they'll charge 50 cents.
All of the ways we've used the cooler to save money:
Overnight at the hospital
On the road
Overnight at a family or friend's home
To the park
Running errands all day
All day sporting event
Overnight in a hotel without a fridge
Make sure to check out this LINK for tips on packing and some great road-trip recipes.
You can also use it to incubate your homemade yogurt (look for how to in a later post)