The MG3 has an internal combustion engine that behaves like any other internal combustion engine. In order to preserve it and keep it running efficiently, it needs to be at optimum temperature ESPECIALLY when the outside temperature is below 12°C.
I'm like you: I start the car in autumn/winter weather conditions and shortly afterwards the combustion engine starts up (like the starter on an old car). After 2 km, my fuel consumption on this route sometimes approaches 15 litres/100.
After 6 to 10 km, the combustion engine has reached its ideal temperature, the electric motors have done their job and my fuel consumption is now just 4-5 litres/100.
Only in summer and at temperatures above 12°C will you be able to drive up to 3 to 4 km on electric power alone, as long as you're driving at less than 70 km/h, on a fairly flat, level road and without air conditioning.
Finally, I suggest that you use ECO mode, regeneration on 2 and of course any abrupt or sporty driving and finally.... you'll see that your fuel consumption will be around 4.4 L/100.
You should also check your tyre pressure (at least once a month, as Kuomo tyres tend to lose a little more air than other tyres) and obtain a pressure of 2.6 bar instead of the 2.5 bar recommended.
Also alternate the type of fuel: 1 full E10, a full SP95 and finally a full SP98.
If you buy your fuel in the same shop, sometimes the quality of the fuel is not the same because of the additives used by the oil companies.