I keep a bag of trail mix and a couple of bars in the cabin of the car. I've got 2 or 3 days worth of food in my GHB, and some snacks in each of the hiking packs that also live in the truck. There's also plenty of water and fixings for hot drinks in there too.

We always repack the snacks before and replenish immediately after a hike, so they're good and fresh.