We travel a decent amount and these have been our strategies to save time and money on the road while also maintaining healthiness and satisfaction.
No refrigeration required: fruit, nuts (we get the big jar of mixed nuts at Costco), jerky (bacon jerky is pretty tasty, discovered that on our last big trip).
Cold stuff to be eaten cold: yogurt (we like to use plain full-fat and flavor it ourselves with fruit preserves), premade shakes/smoothies (my girlfriend likes this one:
http://www.primallyinspired.com/chunky-monkey-breakfast-shake/) in mason jars
As has been said, slow cookers are great. Prepare everything at home beforehand, and then pile everything into a giant Ziploc bag and freeze it together (sometimes I'll put spices/etc in a separate small baggie if it makes sense). Then bring it in the cooler and when it's time, just dump it in the slow cooker and dinner will be ready when you get back to the hotel room after a long day of whatever. Easy. We've made stews and chili and other similar stuff in this manner and it works great.
Equally great is an induction cooker and an appropriate vessel to use with it. Presumably a pressure cooker in this scenario would be excellent as well.
An insulated cooler works great for transporting cold things. Best practice I've found if you have stuff portioned out in pyrex or mason jars or whatever, is to freeze everything beforehand, cover it all with ice, and then latch it up. If you don't open it, that will last over a day at refrigerator temperatures or below. Then it can either be refilled with ice, or the stuff can be dumped in a fridge, and reheated at will in a microwave.
On longer trips, bigger ones are wonderful (I have a badass old indestructible metal one my grandpa gave me), but for a day or two trip, a small plastic one works fine and takes up less vehicle real estate.
In a pinch, as someone else said, one of those insulated bags from the grocery store can work too. I once kept some frozen leftovers cold for nearly 24 hours in three layered insulated bags (but it was a mess because plenty of the ice melted, a hole got poked in the bags, and got my car's back seat all wet; learning experiences...).
We do occasionally eat out on trips, but 95% of the time it's Chipotle. An extra $2 gets you double meat, which I've found is enough food (it's a LOT, a waste if you're not quite hungry) to power me through up to 18 hours of driving.