DF is truck and bus obsessed. Every time we drive somewhere he has to point them out. "School bus! City bus!" He got a book about trucks for his birthday and now he knows about various kinds of 'diggers'. So we get to hear about them, as well.
This is much better than having him tell me how to drive.
This has nothing to do with trucks, but I should say that I'm just astounded at how his vocabulary is growing. We have an alphabet book where each page represents a letter and has various objects that start with that letter. He 'discovered' it this past weekend and even from the first he knew about half of the things in there.
He is always surprising us.