Auto power environments are actually very rough -- 30% (or more!) swings in V+ a nominal 12V system, noise injected by the points opening/closing and the 30,000

Auto power environments are actually very rough -- 30% (or more!) swings in V+ a nominal 12V system, noise injected by the points opening/closing and the 30,000V coil generating a spark, the old mechanical-switch voltage regulators causing a giant surge, etc. Honestly, it's kind of amazing anything lasts in that world. I go through an in-dash CD player every few years. (source: restored loads of aircooled VWs over the years.)