It doesn’t take much to throw a modern engine off its game when it comes to fuel consumption. Modern electronics control just about every function of today’s engines and a single sensor that is giving the on-board computer incorrect information can throw the tune way out of whack without affecting the way the vehicle feels to drive. The best advice is to have the car scanned by a workshop with the appropriate equipment to see if the car’s computer has detected any faults or glitches (which it will have logged). This is a vastly better approach than simply replacing parts at random and hoping that the problem will go away. I agree that 14.5 litres per 100km is too much fuel for this car, so something is definitely wrong, especially if the consumption has suddenly increased without any change in your driving habits.