I now really like the game "I Spy" in the car. The first time we played it was on our drive from Oklahoma to Ohio, but I didn't always understand the idea. Since then, though, I have become really good at it, and the first thing I usually ask once we get in the car is, "Can we play I Spy now?"  Of course Daddy makes me wait until we're out of the garage!
Of course, it's winter, so the games aren't always that exciting - we have a lot of "I spy with my little eye, something WHITE".  And it's usually the snow!
Although I have recently tried to be tricky.  
"Daddy, I spy with my little eye, I spy something white!"  
"Is it the snow?"  
"No."
"Is it that sign?"
"No, it's the snow over THERE!"
Ha ha!