He is starting to recognize places and knows where we are going for the most part. That knowledge apparently inspires his quest to know more...
Jack: This is the way to Rita's, Mommy. Why is this the way to Rita's?
Me: This is the shortest way to get there and it's the way the road goes Jack.
I can't answer that. Maybe I could delve into something about city planners and roads. Or something about horse trails from a long long time ago. But I really don't know the history of these roads well enough for that. I end up not answering him or repeating myself.
Jack is also interested in where all the other cars are going.
Jack: Where is that car going Mommy?
Me: They're probably going to work.
Jack: No, they're not.
Me: Yeah, I think they are.
Jack: No, they're on the same road as us, so they're going to the gym too.
Me (in my head or sometimes out loud): Well why did you ask me if you already know where they're going?
On another day, he asked me what I was doing and I told him that I was speeding up to get in front of a truck (a dump truck). That opened a whole new can of worms.
Jack: What truck Mommy?
Me: The one behind us Jack.
Jack: Where is it going Mommy?
Me: He's going back to work.
Jack: No, he's going home.
Me: It's the middle of the day...he's probably going back to work.
Jack: No, he's going home. He has a little boy at home who is 3 too. He's going home because he is going to take his little boy to the Little Gym.
Jack wins again. But I have to love the imagination he has.