The trip when I went 902.1 miles without fuelling was in August so it was hot.
This year in the Pyrenees I noticed that one morning it took about 12 miles for the temperature gauge to reach its usual level even though it was a warm day, but it was downhill all the way.
Please be reassured that I dispose of banana skins carefully for fear of causing accidents.
Great effort marti30 , some say summer or warm weather help economy but by how much i have no idea. just can smell the diesel exhaust more on a very cold morning. when it's hot you don't seem to notice any smell.
like you noted the motor takes a while to warm up even in warm weather unless it is under load (climb a hill , pull weight ) as motors start to develop power & torque under load,
have noticed i now get 1,200k between fill's without trying as no heavy traffic.