DD1 (3.5) is a road trip champ. She's always done really well in the car on road trips. I pack snacks, foods, activities and only have to pull the iPad out towards the end.
DD2 (15m) has days where she will just scream and scream in the car. We have a 7 hour road trip tomorrow and I'm a little scared! I'll have all my usual bag of tricks plus 2 bottles ready for her.