What Kristtriple says is roughly correct. taking it too easy wont make things better, Being a Long distance HGV Driver ive been on upteen fuel saving Seminars. and it takes time,to get the best technique that works for you.three main things are to accelarate quick (not a formula one start) and get in to the next gear which the car can handle ie 1st to 3rd leave 2nd out. or start in second, think in advance can save alot of fuel, stay in the Highest gear as along as possible avoid stop starts when coming to traffic lights, it better to accerate from 5 mph as from 0mph this saves a lot of fuel. Reach a constant Speed and stay there
The ecoboost engine works on the same principle as a desiel engine when decreasing Speed, in that as Long as the clutch is engaged and gear is in it starves the engine of fuel till it reaches the Computer programmed low revs, then lets fuel in the engine otherwise the engine would stall. you can see this in the display when you take foot of the accelerator it will go to 0mpg. using this techniqe alot will save fuel. Coasting with clutch in uses fuel as the engine is recieving fuel to Keep the engine going.
Acelerating and then braking straight away wastes fuel, and on roads with a lot of hills turn the cruise control off and acelerate manually, Human sensors are a lot better then Computer.
This takes alot of pratice, But after a while you will be doing it automatically and save a lot of fuel, and you wont be slower then the car that just shot past you and stands at the next traffic lights and you come up behind with out stopping and accelerate away when it goes green, as you know you will over take him again cause he has to fill up lol.
If the figures don,t get better then i would speak with you dealer.
Sorry if i am telling you to suck eggs but People don,t get taught this.
The c-max is as of yet the best Petrol car ive owned for fuel consuption, for its size weight and engine. ive owned. The readout on the Display is only a rough guide and not what is really being used.