Once when I was little my mom asked her to start her van up for her so it could warm up. I did, then took out the keys and brought them back.
The van was still running.
One of my cars had the power windows and AC on the same circuit. A short in the wiring caused it to blow the fuse and any new fuse you put in, leaving me with no AC and windows that wouldn’t go down just as we were getting to the peak summer highs.
My worst cars dashboard stopped working, it wouldn’t let me put it in park, it wouldn’t let me even start and it got to the point where it would be cheaper to just buy a new car. I sold it for $800 which is what I initially payed for it.