I always here people complaining left and right about not having enough company coins. I honestly only had issue with it once, then I started doing the weapon assignments.
All you need to do is complete weapon proficiency/mastery assignments. I personally have every single assault and medic guns full golden, apart from shotguns every support gun golden and all the bolt action snipers golden. With that I have every single vehicle and gun upgraded to the max rank and still have 13000+ coins spare, only having to spend them on cosmetics.