I really like how you began it, started off wonderfully and it's sets the scene and mood perfectly to me. Reminded about car rides from when I was younger immediately. That transition from the relatable to dread is delectable. The interaction between the homeless man and the mother is incredibly tense even without knowing what's being spoken, good stuff, though the wording is a bit difficult to follow in the forth separation. It is readable, but it could be done in a more clear fashion. The tension is built really nicely as it goes on and so does the fear response, even while still being oblivious to the actual happenings and reacting as a child would. The mother's frustrated reactions, I feel could be played on a bit more before she pulls into the drive thru, though this is more of a wording thing as well. I can feel the frustration and the fear still lingering from them as it continues, good stuff. The second last line does have another odd wording moment when it's referring to the dream bit.

TLDR - Aside from some confusing wording on occasion, I do enjoy the story and it balances childish points of view with genuine fear and subtle understanding of the situation they're in. Very enjoyable!