Link to the Savefile used if anyone wants to mess around with it. (https://drive.google.com/file/d/1g6Hi...) Note: you need to load the save twice to properly load in both CJ models. Also there's some all-proof vehicles in the garage nearby
Glitch that creates a duplicate CJ - • How to reset all of LS and Badlands missio...
A strange effect I found recently which allows you to go airborne in most vehicles. You will need to place fake CJ behind you whilst next to the dumbbell exercise and assassinate yourself. During the struggle animation begin the exercise. You will fall to the ground but you will not die. Then by answering a call you'll regain the ability to stand up though your movement is locked on the spot. Then whatever vehicle you enter next will prompt the dumbbell exercise to begin whilst your inside of it. Ending the exercise will give you this strange effect.
Certain vehicle make you levitate whilst others push you to the side whilst others go completely haywire. Iv'e noticed the lighter/smaller vehicles give you the craziest amount of air-time. Also it seems to help if the wheels of the vehicle lift off from the ground so using vehicles with hydraulics installed helps get me in the air. On the contrary heavier vehicles struggle to get airborne.
Unfortunately the effect isn't saveable and once you exit the vehicle through any means the effect will end. Also a strange thing I noticed is that it's possible to take fall damage inside of flying vehicles if you slam the ground at a certain angle. Also because the game doesn't consider you to be in an aircraft or using the chittychittybangbang cheat, it is possible to rise above the normal height limit.