I do one hour road trips (2hr there and back) almost weekly with just me and DS (almost 14 m/o) and his current carseat favorites are books, an old cellphone, books, a pinwheel, and more books!! His latest toy that he loves is a 5mL syringe, though it is probably not the safest toy...He absolutely loves pushing the plunger in and out! I find that alternating the types of toys (e.g. book, then noisy toy) works best. DS likes it when I point things out to him (cows, cars) and I have to pass big trucks very slowly because he just loves to look at them!! Also let them have a good run to tire their legs out before the trip, and for the longer trips you certainly need rest stops and snacks!
HTH!
