I think CM's showroom is broken. It's not the first time I tried to change the direction of the flames with opposite values but the arrows don't move. Especially when they are aimed at rather unconventional directions, like the top of the vehicle.
Seems like it's interpreting the coordinates differently for some reason, as I remember it (vaguely ) I set the flame positions using the showroom and the values seem kind of odd to me but they work in game so I assume they're correct. I did wonder if there might be a setting in CM that affects flame coordinates but I can't find anything.