The cylinder deviates from the direction it supposed to go. For spheres, it goes perfectly straight.
This has been a problem because this becomes noticeable on four-wheeled vehicles that use cylindrical wheels especially at high speeds.
To reproduce this bug, get a basic cylinder and apply force or impulse. Applying torque or angular impulse produces the same result. Get a sphere for reference of how it should behave.
For comparison and tracking deviation, first get the starting position of the parts. Then if it moves on z axis, track the difference between starting position x axis and current position x axis per frame.
Cylinder vs sphere demonstration.rbxl (65.9 KB)