When my oldest son, Clay, started driving we tried to teach him both the importance of driving safely and of taking care of his vehicle. We got him a used car to get to and from school. Often, when the whole family went places together, Clay would drive the family van. Our town is small and has "dips" at nearly every intersection for water to flow down during rain storms. Clay would never alter his speed when going through these dips, no matter how many times we asked him to nor how deep the dip. The last time I asked him to slow for a dip he was apparently tired of being nagged and said "Mom, the dips just don't bother me!" Amazed, I had to answer, "It's not you I'm worried about! It's the car!" Without our giving Clay a reason why he should slow for the dips, he had assumed it was for the comfort of the driver and passengers!
Maybe, when kids keep asking 'why?', we should answer with a logical response, and not the standard "because I said so!"