BF4 Vehicle Sensitivity

The sensitivity setting in the game is probably one of the most personal things you have in this game, as its a very personal preference how we all like the movements to react to our e.g. mouse/controller inputs. 

It also changes as you gain experience with controlling your soldier and the various vehicles in the game.

So best approach is typically to start with a low sensitivity.  And then as you gain experience and comfort in controlling your soldier and vehicles, then you slowly but surely can start to increase your sensitivity level.  Like you already observed yourself, you may quickly find that e.g. the tanks in the game are at times reacting to slow or turning the turret too slow to your liking and control abilities.  Well then its time for you to increase the sensitivity for that in the settings. 

But trick is here then only to make a minor increase at a time.  Because each time you increase the sensitivity setting then it will take you some time to truly getting the habit of that baked into your "finger memory" so you again with the increased sensitivity feel fully comfortable and in control in most game situations.

And then at a certain time you reach your personal limit, so when still making a small incremental increase to the sensitivity level, then you hit the breakpoint where you then do not appear to be able to do any better, but actually instead now too often loose the gun fight or the control of your vehicle.  Then its time just to decrease the sensitivity ever so slightly and then stay with that.

Again, the sensitivity setting is a very personal thing and best is to test out with yourself what works for you.  And then having the patience not to push it up too fast.