S.G.
In the car we always talked about the things we saw outside, sang songs and played silly word games. It helped develop language much faster. Most of the grocery stores we shop at have cookie clubs for the kids, so I would wait until they were getting bored and fussy, then get them their cookie. If you are bringing a snack, don't give it to him until he gets bored and fussy. If we were someplace like Wal-mart we would visit the toy section when they would get bored, then let them carry something from the toy section around in the cart for the rest of the trip.