Food costs can add up quickly on a road trip. Don't think you can eat packed sandwiches from a cooler every day either, because you'll get sick of them eventually and find yourself eating out at every meal. The key is to mix it up. Research the restaurants of towns you'll be visiting or driving through, and seek out inexpensive cafes and delis to avoid having to live on fast food. Couple these great local finds with a mix of packed lunches and breakfasts on the go, and you'll definitely see some savings. Keep plenty of snacks on hand to make sure you're all not starving when you arrive at your location. Be sure to get them from a grocery store instead of a convenience store, because you will pay extra for the convenience.
The Internet has tons of Web sites that offer discounted meals through an easy download to your smart phone. Think of it as an e-coupon of sorts. Typically, these deals are based around a city, so scope out online deals in the areas you'll be visiting and take advantage of the savings they offer. Groupon.com and Scoutmob.com are two sites with lots of great deals. If you're traveling with youngsters, look out for restaurants that offer discounts (or even free meals) on certain nights to kids under 12.