Traffic and stop start journeys / short journeys make a huge difference to consumption.
I travel the same 12 mile route several times a week. A / B roads but with a town with lots of junctions and traffic lights.
Last week, at rush hour, with a cold start I got 22.7mpg.
Late at night, no traffic and the lights were with me, barely slowed down, but normal road speeds, I got 34.9mpg.
This is not a scientific test but more or less repeatable most days for me.
Cold starts, heated rear windows, heated seats, headlights, blowers etc etc all add to the load on the engine and fuel consumption suffers.
An easy 100 mile motorway drive a couple of weeks ago , in the day, saw 39mpg.....