Perhaps your parents can drive their own vehicle, or you can rent two smaller cars if separation is needed. Although, I do think time spent together while driving between destinations can often be the most rewarding!
It’s great to give everyone a role to play in the car, and exploring a city. If you have multiple drivers, you’ll want to switch up the roles as well. Give the children something they can easily manage and will enjoy doing.
Have a place for everything and instruct all passengers of where things belong and their roles in keeping a tidy car. Every time you stop the car, instruct everyone to collect any trash and dispose of it. These good habits will keep a tidy car.
Allow your child to use their device but restrict their time on it. An hour on the device will give the grownups a bit of quiet time and Nan and Pop some time to snooze.
I know this can be hard when your parent’s music tastes are so far out of your generation, and your children’s choices, you just don’t understand. See how you can weave music into the upcoming travel experience.