We did a 3 1/2 hour trip recently so nowhere near as long. I wouldn't have wanted to have him in the car any longer than that. He's very good in the car but if he got a yucky nappy he sure let us know about it. Make sure you have plenty of room on your backseat free so that you can change a nappy on the side of the road & absolutely everything you could possibly need in the nappy bag.