Average MPG droppings when still

Does this happen to anyone else? I was watching mine before for the first time and noticed it drops, all the way down to around 12mpg if I reset, drive a little bit until it shows up then stop! Does this mean my engine is running really rich or is it normal, surely it doesn't idle at 12mpg?
 
You mean when you are stationary? As you are not moving anywhere you are doing zero miles to the gallon. This is why being stuck in traffic will affect your MPG.
 
Yeah, that's a relief I have never watched it before, I would have thought it would have been a higher mpg but thinking about it I'm not doing any miles hahahhahaha schoolboy error!
 
My last car used to switch to show you gallons per hour when stationary with the engine running. Was always 0.2 at idle.