Car. Truck. SUV?

Jack and I take at least one walk a day- with or without the stroller. He is starting to become particularly interested in vehicles. He knows what a bus is and I think he's learning to distinguish the "big" trucks. I say "car" as the typical corollas and civics drive by, but I'm not sure how much detail I should relay for those vehicles not clearly a "car" or a "truck." For instance, mini-vans. Should I say "van?" After all, what makes a truck a truck is its size or the open back. What about SUV's- they are pretty much a car, but the size factor leans towards truck. And, don't even get me started on the PTg Cruisers. A "SUV car?" maybe. It probably doesn't matter all that much now. I'm just trying to keep things simple, yet honest. I'm sure he'll learn soon enough all the varieties of cars, trucks, whatever. Much like his cousin, Elijah, seemed to learn all the different kinds of dinasours before he was four.