Cop cars not spawning glitch

[VC Vigilante]

I don't know if this is a known glitch, but while testing out my vigilante% runs at game start I try and attain a wanted level as fast as possible like running over a cop and then shooting peds. 50% of the time I can get up to 3 wanted stars and not have any cop cars come after me while driving all over the place. Once I get to 4 wanted stars then the police vehicles start spawning normally again. I do get the odd spawn during the glitch in specific spots that I believe are called scripted spawns like those two that fly out of that side road on the main strip. Usually its on a bridge.

 

I'm also trying to see how fast I can get a FBI cheetah to spawn but I can't seem to get one 90% of the time. I got one within 2 minutes on the PS2 version but nothing on PC at game start.