I guess I never really thought about it before – under the hood is a pretty extreme environment. Yesterday I put a TMP36 temperature sensor on a copper lug and attached it to the battery terminal on my secondary battery (Kirkland/Interstate deep cycle marine battery, group size 34). The sensor’s good to at least 125 C, and as can be seen from the above plot, it got to at least 90 C yesterday. Huge thermal mass, that battery and engine, so an all-night soak in the relatively moderate (45 C) temps of the garage saw it cool to only 50 C. Only.
The automotive environment is a extremophile place. Kudos to the automotive electronics engineers (and plastics, and polymers, etc. infinitum) who design and take responsibility for designing the stuff that makes cars work.