gday! 
im having a desync (?) issue on my side that players’ vehicles’ wheels, engines, trans or diffs emit excessive amounts of smoke. doesnt matter if its vanilla or otherwise. this makes it incredibly difficult to follow a lead. turning shaders off doesnt help either… 
f11 and find partical inpector and turn the smoke down
Thank you very much! Although some servers don’t allow the world editor to be brought up…
EDIT1: the world editor solution works the best!
EDIT2: so, basically, indeed, it is a desync issue. if someone is smoking like crazy, you will have to stop and let people sync their edits and queues. if that doesnt help, ask them to press CTRL+R
ANOTHER SOLUTION is a bit technical and needs explaining. if your gearbox settings (gameplay assists) are set to arcade mode, it may affect every other car, including players! there are still a few gameplay settings that are not yet implemented in beamMP and may cause desyncs, one of them is ignition (start off) and brake temperature (start cold).
if you have a wheel (and a shifter):
Options > Gameplay > Vehicle Behaviour > Default Ignition State = ON (running)
Options > Gameplay > Vehicle Behaviour > Gearbox safety > Throttle and Clutch assist = OFF
Temporary solution is to have this custom tyre smoke mod installed on the server:
It makes the smoke less smokey.
At the very least, you can always just delete players…