I regularly did those sorts of drives, with all ages of kids.
Take plenty of supplies, and be prepared to stop as often or a s little as needed (off motorway, check pit stops)
Remember a handy bottle of water for mum, who will need it if she does lots of singing!
I come from a "story telling" family so I would talk about the places we drove through and tell child friendly tales about them (easy now to look up on the internet). My grown up kids remember them well, and astonish friends with their "local" knowledge! Even a 2 year old will like to hear mum telling tales, however much or little they understand - they will "grow into" the stories.
I've got another 'keen'... Ouch!