New Owner 2013 DIG-S Tekna (fuel consumption query)

Ive recently purchased a 2013 DIG-S tekna and one of the reason for choosing this car was the posted average fuel consumption of 65mpg combined.

However after testing I have calculated I am only getting about 45mpg. Is this normal?

I have tested this by filling the tank and then driving until only two notches left and then filling the tank again. I then used how many litres to fill to the click and miles travelled since topping up. This calculation came to 45mpg. I also noted that from full From a fuel tank the trip computer claims I have 413miles to empty, which with a 41 litre tank works out to be about 45mpg.

Is this normal MPG for a dig-s
I cannot speak for the Dis-g but for the naturally aspirated model I cannot go bellow 4.6l/100 (61.4 mpg) and this on the highway driving like a dead man at 80km/h -1300-1400 rpms. In the city I see a fuel consumption of 6.2 (45mpg). Average though without driving like a grandpa on the highway and in the city it returns 5.9 (47.8 mpg). I've seen numbers of 7.7 (36.6 mpg) if rushed or carying weight and if the A/C is on.
When was new mine was a bit more economic but when it passed 10000 kms it went up a bit, now showing the values above. I always believed that in practice the Dis-g would chew more for the reason that it has to run the compressor also which could also translate in extra load on the engine resulting some extra fuel consumption. The 65mpg are theoretical numbers, not hard to achieve if you drive on a highway flat at 80km/h without load and any electric and mechanical power consumer on. It's all about marketing, also take in account the recent VW scandal, you know what I mean. ;)
As for the fuel tank, on mine it empties after 31-34 liters, and I never filled up to 40 liters or even 38. Always it runs dry without any lines left on the fuels gauge at 34 liters.
Not sure if this makes any sense or if you could check this also, but might worth a look.
On the other hand, the fuel quality plays a major role. From some petrol stations I see more mileage and from others I see less (stronger the pump smell, usually better the fuel in my case).
I have noticed that about the size of the fuel tank, I wondered whether it has a large backup after the fuel gauge runs out. Or if the specifications are just incorrect. I have started to drive like a granny and keep the revs under 2K and if see if that makes a difference. I have also been using supermarket fuel, I will switch to Shell in my next fill up and see if it makes a difference. Would putting Super unleaded in make any difference?
I truly don't know if that will make any difference. Tried once I believe but never checked or remember. I might try and see though on such small engine I doubt it will make any difference.
a good trick on keeping the fuel down is to accelerate on downhill and push as little as possible uphill. I have an ELM327 with the Torque app on my android and with that I can see the accelerator position. Keeping it at 5-10% is best, at least for the CVT. At that stage it just keeps the transmission belt coupled and it rolls on the idle power.
45ish is what we get from our DIG-S manual when the wife drives which is fairly gentle

soon drops when I get behind the wheel mind!!

Asda fuel for us.

Driving like a granny does not always means best MPG, sometimes it can have a negative effect.