For Christmas, I took a little trip up to Houston. From here, it’s about a three hour drive (well, two-and-a-half, but, you know), and about twenty minutes into it, I couldn’t keep my eyes open.
Then I ate some peanut brittle, and I was wide awake the rest of the way. Don’t know if it was the chewing or the concentrated sugar, but that woke my shit up!
So, when you’ve got a long drive, what kind of foods do you find wake you up and keep you alert?
Corn nuts! I defy anyone to fall asleep while eating these brain-jarring morsels. Chase it with a Coke and you’re up for the duration.
I tend to favor Jolly Ranchers and plenty to drink. Going over bumps with a filling bladder works wonders at keeping you awake.
Shock Tarts or Hot Tamales.
Chocolate-covered coffee beans.
I like Gobstoppers
beef jerky
Fruit chews (like Starburst), then cashews, washed down by tea (tea doesn’t need to stay cold to taste good).
Tic-Tacs. I can’t drive for long periods without some sort of mint.
Swedish fish and Dr. Pepper!!!
Enough sugar and caffeine to keep you goin’ all night.
Cheddar Cheese-flavored Combos. These are my favorites on long car trips because they’re fairly filling as far as junk food goes, and you don’t get your fingers all nasty with cheese dust.
Red licorice. Not messy, full of sugar. Perfect.
StG
Snacks with protein, like peanuts and sunflower seeds. Caffeine (although the comedown can be bad from the standpoint of tiredness vs alertness). A bit of cocaine works wonders as well 
(just kidding, just kidding!).
I have a few different amphetamines on prescription (ADHD), and I would take those for the really long trips except that for some reason they make me depressed and (to an extent) drowsy. Unfortunately, most of my medicines and favorite recreational drugs (mostly legal) either have a depressant effect or negligible effect on the CNS (central nervous system) (as opposed to a stimulant effect on the CNS, which is what you’d be shooting for if you want to be awake and alert). Nicotine could do the trick for a little while, but I myself am wary of smoking either (a) in a non-social situation, (b) more than one cig every month or two, or (c) both.
Oh, I drink sports drinks when I’m driving tired, too. I’ve chugged some God-awful flavors of Gatorade in the name of alertness.
Gummi Bears!
I like to get a couple rolls of SweeTarts and pop 'em one at a time.
I second the Gummi bears but only the kinds that are not made in in the USA, they are too gelatiny.
Peanut mm’s are a good choice too.
For a salty snack, pretzels or cashews. And always a diet caffeinated soda.
Nothing keeps you awake like a carton of ice cream between the legs. I much prefer loud music and beef jerky.
Munchos and convenience store capuccino. I only eat/drink those on road trips, but I love them.
Those sour Altoids, the lemon ones, not the tangerine. I also love to chew gum to stay awake while driving. I prefer either bubble gum (any brand) or Big Red. A beverage is also a must; either fruit juice or ice water.
I buy blowpops for a road trip. I like to suck on them til I get to the gum. I never bite into them.