&gt; What do you tell the cluelessly naive good guy engineer about his results? Would he really only test the car under test conditions? Does any engineer with even the slightest grain of curiosity test only the one mode that he&#x27;s supposed to?<p>While I agree with the rest of your posts, I can&#x27;t let this one slide.  This happens <i>ALL THE TIME</i>.  I have to beat engineers senseless over this on a regular basis.<p>&quot;Just because it passed one test, one time, does not mean you are done.  It has to do something sane even when the rest of the world is coming flaming down around it.  Crashing could be the sane thing to do; logging could be the sane thing to do; returning very obviously insane values is non-ideal, but might be your only option.  A couple of safety checks are warranted.&quot;