no, while you are in a car, seems the be a glitch but get in a car and your shootable, on the ground your a ghost for shooting.
its funny, you engage passive mode and your instantly unshootable.
when you release passive mode it takes 10 seconds (im not sureif you are shootable during the 10 seconds but they never do, probabl;y becuase they dont know your comming off it) snap shoot them and engage and instantly they cant touch you. must be hugely frustrating, i killed 5 out of 4 of them wnd they respawn and i just run after them.
just be carefull because they eventyally work out they can runover you. good for trolling though.
i also had a mob of 3 or so camping the spray shop killing everyone, sat back, sniper rifle from a building top and picked them off. too dumb to figure out wher i was shooting them from and kept trying to camp the spot after respawning. eventyally a chopper shot them up with missiles. and me