for me, i have an aftermarket alarm and it has passive and non-passive arming, which means if you don't set it yourself, it can arm after 30 seconds or arm+lock after 30 seconds. with that being said, i also have the window modules tied into the alarm. i was in a gas station once, threw the keys onto the seat and started filling up. i'm looking the other way when i hear a faint beep. i recognized it as my alarm but was confused as to why it sounded so faint. i looked down in my pocket, but it wasn't there. so i look up to see the windows rolling up. i ran to the door, but just like the movies, just as i threw my hand out, it closed. luckily i was 3 blocks from my house and i knew the gas attendant. he laughed, i finished filling up, and walked home to get my fob, which still works to unlock the door, but the alarm went off when i opened it.