That is a creepy story, @rayt2. You certainly incorporate the prompt. The repeated request to hear more from 'Grandma' gives energy to the narrative. Readers are thinking, "Yes, more!"
The difference in decomposition of the bodies adds to the creepiness and the credibility of the ghost theory. The one part that is a little confusing is the gas tank. It's filled with water, but then later there is a statement that there wasn't enough gas to go 100 kilometers. On re-reading it appears to make sense, because the implication seems to be that the gas tank was not large enough to hold gas for a 100 kilometer journey. But it did take two readings for that point to be clear.
You did a good job in delivering a creepy ghost story. Thank you for sharing this piece with us. We very much appreciate that you actively engage with other authors.