I can remember as a child that the journey was part of the holiday but you here parents nowadays complain how the children play up on the trip whether it be half an hour or several hours. This must be IMHO because the parents themselves have no idea how entertain them and are basically impatient about arriving themselves which brushes off on the children. I have to disagree a little bit here
What I've noticed around my way .. it's more because parents scheduled every minute of their kids day .. that when there is down time .. whether it be on a car trip, in a restaurant .. or even in church .. they don't know how to use their imagination or behave properly and act out and many parents don't correctly deal with bad behavior.
In a way that is what I was referring to but in a different way. I can remember when I was 8 - 10 that we had a series of books called I-spy and they varied from wildlife to road signs to pub signs that one encountered on a journey.
I can remember interacting with driver/passengers in the car in the attempt to complete the booklet before we arrived.
If we did not have the book then another thing we used to do was try and spot so many cars of a one colour or make or even down to model of a particular make. Even to this day it has made me aware of the different types and models of cars that many of my female contemporaries could not identify, as a non driver I still use this entertainment to while away a car or train journey.
Number plates were another thing we did especially if was around the first of August which was the date in Britain that the new number plates used to come out so it was a competition in our household who would see the first "new car" of the year.