What's with the second wheel?

My son like all other toddler boys out there has infatuation about wheels. Whether it be Lego blocks or dump trucks or the grocery cart, he spends hours examining how the wheels turn around. Last week he saw a traffic speed alert on the road mounted on a pair of wheels and turned around and asked me - "Where is the second wheel". After a minute I responded - "Its broken. We will fix it tomorrow". Next day - "Papa - Fix the second wheel" :)

This happens every day. His favorite movie is Cars and he cannpt go to sleep nor eat without his McQueen. On Christmas we gave him a Cars cardboard puzzle and he quickly put together McQueen and Sally and then stopped. The rest of the puzzle was too boring for him.

I have seen that cars and trucks are easy way to make him learn almost anything. For example, he wouldn't touch the Lego blocks if I didnt have the wheel parts in it or he couldn't put together a simple car using few blocks.

If you have had similar interesting stories, do post them here or give me a pointer!