M62 4.4 fuel consumption gone down
 

Thinking caps on.. My 4.4 M62tu has gone from 19mpg average to 16mpg average in the last few months. I've also noticed that the temperature gauge sits slightly below vertical most of the time.
Is my motor running too cool?
I know the guage is buffered between 75°c and 110°c when needle is vertical but my diagnostic shows the engine temp never going over 85 so is the fuel system stuck in a closed loop and over fueling because it thinks the engine is not up to temperature? Is that how it works?
Car runs fine otherwise.
I've recently had a new set of tyres too but the car rolls easier and the steering is lighter so I don't think think it's them causing the poor MPG.
What do you think?

M[emoji239[emoji2392]]2 [emoji2392].[emoji2392] fuel consumption gone down
 

Happened to me : struck open tstat ran open loop for months until cold weather and didn't get cabin heat.

The non gauge would go to vertical telling me everything is good. Lying piece of shit.

Winter gas formulation will kill mpg on some car models. A buddy of mine that logs every tank noticed every October his mpg dropped about 5 mpg until may

Mine does the same thing but not that drastic. Winter fuel sucks. Summer fuel gives better MPG.

How old is the fan clutch? Check all the belt pulleys for drag.

gauge inaccuracy & bad? fan clutch workarrounds
 

My mpg stays about the same, winter or summer, because I actually spend more time driving short hops and doing more stationary testing in summer, while testing less and driving on longer trips in winter (to the family compound during holidays and birthdays...mostly in fall & winter).

But, since I use the Torque Pro app on a dash-mounted Android tablet, I can monitor actual coolant temperature at all times, and see where the T-stat opens and if I'm in closed or open loop...better than relying on the BMW "guess-'em" gauge.

And, one of the first things I did when I traded for my X5, was to replace the failing fan clutch (with deteriorated blades) with an aftermarket electric fan, and added controls so I could change the fan speed at will, or turn it off completely (and to reduce noise). Now, in cooler weather. I can turn the speed down low, relying mostly on the auxiliary fan (replaced a few months ago), and in summer, turn the speed up to 100%, in stop & go traffic. In both seasons, I'll sometimes also turn the fan off at highway speeds, to conserve electrical power, as it becomes redundant due to free airflow.

IIRC, my mpg went up about 2-3 mpg, after installing the fan, and obviously, the wear on the waterpump bearing was instantly reduced, by eliminating the fan clutch. A win-win situation.