I don't know what it is about toy trucks, but my son absolutely loves them. He gets on his hands and knees and pushes them around the living room into the dining room, kitchen, bathroom, up the stairs, into his bedroom, and then back down and all over again.
It's so adorable. When he doesn't have a truck on hand, he finds a book, random toy, or even a cup to push around like a truck around the house. Again, adorable and quite imaginative.
What makes it even more funny though is he oftentimes does not realize trucks probably should be facing forward in order to drive around. Oh well. He will figure it out someday.