We recently travelled by car to Provence and we were recommended to travel in the evenings so the kids can sleep. The trip is roughly about 5 hours and we managed to do it in about 7 hours.
We tried to keep the children 'in routine' so we stopped to change them into their 'pjs' at the same time they usually do (bath time was moved to the next morning) and we had dinner and let them play & run around as much as we could.
Once we were on the road again we used this as 'bedtime routine'. Reading stories & playing with toys.
Although once we arrived at our hotel both kids woke up, we did find travelling in the evenings easier in terms of preparation. They had less energy, we rotated less toys, there was not as much crying & screaming due to boredom & being held by the carseat and the motion of the car is proven to make children sleepy so I would recommend it, if you are confident to drive in the evenings. Luckily we knew the road/journey as we had both driven to and from Aix en Provence a few times.
Be realistic: You won't be making the trip in the recommended time that your maps stated it would take. Always add roughly 2 hours with numerous stops en route.
Be Flexible: Preparation is always key, but travelling with kids is unpredictable. Stop when they ask or when you can sense they are restless. Follow how they feel. Take advantage when they are sleeping to cover distance and be open to stopping often when they are awake. Travelling is tough for them so make them feel as comfortable as possible.
Pack their favourite toys, but be smart. Don't pack building blocks or a train track as this will be rather difficult to build whilst being buckled in and will cause additional frustration. Books, sticker books, play dough, drawing books, dolls or figurines.
iPads/tablets can be educational. I don't believe in using them for hours, but let's be honest-it does help (for our own sanity too). Educational games, drawing programmes, sing along songs.
Reward good behaviour-however you feel is best for you. It is difficult for kids to sit in one place for hours, therefore, it's important to tell them that you are proud of them for being so well behaved and talk to them about where you are, where you are going, what you are going to do-this keeps them occupied, engaged and you won't believe how it kills time. We encourage Chloé to look outside (if it's not dark) when we are in the car and we try explain all the villages and sights that we drive past.
Calming music does the trick-this can be easily found on radio stations if you search or on your phone-this will benefit a nervous traveller as some kids fear travelling and may even suffer from motion sickness.
Don't forget the doudous (comforter) or an object from their room that gives them a sense of comfort and familiarity.
Don't be tense-travelling can be hard for us parents too. Trying to remember if you packed everything, hoping you didn't leave your charger or your childs' diapers at home. I always pack for three people (sometimes four-yes I do Hubby) so I know the uptight feeling you may experience, but children can feed off this energy so try relax. As long as your family are safe, that top or additional diapers that you may have forgotten can be easily replaced.
And finally, if you don't share the driving with your husband/partner, don't feel bad to sit back and have a snooze too.