My perspective about the vehicles was if FM saw them earlier in the morning when she looked out the window and then not too long after that WT turns out to be missing and the two vehicles were involved in his disappearance, wouldn't that have been very important information to jog the public's memory with?
What if whoever owned the vehicles grabbed WT and took off with him, wouldn't LE want to know if anyone observed them speeding out of the area of Kendall, and in what direction they appeared to be heading in etc.?
In the U.S. if a vehicle is involved in a child abduction it would immediately be an Amber Alert.
It would be imperative to locate such a vehicle as quickly as possible.
Just my take on it anyway.