Little circuit to turn off start&stop of my car
Go to your local dealer and ask them to turn it off for you. These sort of features can all be controlled by the dealer, and often times they won't even charge you for a small change like that.

While I like to dabble with electronics myself for various applications, I'd steer away from messing with the electronics of my car unless I'm 100% sure what I'm doing, and that it has no nefarious effects elsewhere.