It runs the fans a lot.
The fans run a lot at idle due to the low flow from the coolant pump due to low RPMs.
I don't sit and idle in traffic a lot, but what I do is pulse and glide. When I pulse and glide the car fans appear (unconfirmed at this time) to be running.
The fans run becomes the temperature sensor is hot.
It's hot because there's not a great amount of flow coming from the pump at lower RPMs.
To increase flow would mean to increase RPMs, and therefore affect fuel economy.
The test I did today was pulse and glide and simply watch the gauge, the gauge rose.
I then held the RPMs up with 0 throttle rolling down hill and as expected the temperature dropped below it's standard operating temperature.
Essentially the problem is the pump doesn't flow enough coolant through the thermostat if the RPMs are low, the fans run but as they are controlling to a sensor in the coolant before the thermostat, they are trying to cool with no coolant due to low flow.
I'd love to be able to monitor coolant flow, and show the problem but the above driving shows the issue.
The fix is of course to increase flow so that pulse and glide doesn't get a lot of heat, and the fans are off more (thereby fixing the fuel economy).
Since I only filled up recently, I'll be testing fuel economy with no pulse and glide this tank, to see if the increase in fuel due to no pulse and glide is measurable (giving two results in theory - how much does pulse and glide really save me).