We used to have a pack of cards with different pictures on them with things like tanker, coach, church and the like that you could spot when driving. They each got five cards and the first to get all five won. Not sure if it is still available though but you could make up your own set. It does need more than one or you can join in but it worked well when we had three children.
We did also play number plate bingo using a bingo card and the driver calling out the last two numbers on car number plates as they went past, or if we passed them, but this no longer works with current numbers although someone might work out a variation.