Everybody knows by heart every random phone number they might ever need to dial. (This of course I learned from classic movies, made before there was speed dial, let alone mobiles. I don't remember anyone in any movie ever needing to pull out their address book or notepad before making the vital call.) Just as they never need to lock their car. Just jump out and leave it there; it's not as though anybody would ever steal an unlocked car, or even steal anything out of it!