@DepArshia It seems you may have messed up when installing new vehicles? Did you make sure to drag all of the vehicle files into the latest patch day on OpenIV?
All were listed as invalid models: fbi, fbi2, sheriff2, riot, police4, firetuk, ambualnce, police, policeb, policet, pranger, sheriff, crusader, sanches, scorcher, polmav, buzzard, policeold1 & 2
Send a screenshot (search snipping in windows search bar) of your latest patchday in OpenIV