What I've found is that if you touch anything right after you jump you die but if you jump from a place where you are mid air all the time (slope or something) you will survive.

edit: Also Sayonara Salvatore jump can be done like this:

Sorry for 2 vids, also note that if you land your first jump too early after you super jump you will slightly touch the piece that stands out in front of you = RIP so its still safer to do it with a car but I've had few times when even then I died.