Observed cold weather MPG difference

http://i.imgur.com/dHtTpJy.jpg
This is highway driving with winter tires on bare road at 109km/h, at -26c, with octane free gas.
I later speed to 125km/h but the consumption seems the same.

 

Where in hell is it -26oC?

 

-26 C Not too bad. We're at -12 F now, and it's just starting to get cold

 

Im in canada. in gaspe it is even lower, -44c.
at -30c/-22f , the suspension is all stiff, the steering is heavier, even the gear shift won't spring back as easily...
I read in the manual that when the temp is cold I should wait for the READY light to stay on before driving off, surprisingly that light only flashed like 2 seconds, but it was no way ready to drive at that moment...

 

Better you than me

Off topic, but years ago we went around the Gaspe Peninsula. What a beautiful place that was.

 

I'm surprised no one has mentioned "winter" gasoline. Most, if not all, gasoline blends are reformulated for cold weather driving. As a result, gas-powered engines are easier to start in cold weather, but at the expense of MPG, due to the BTU's available in winter gasoline. Perhaps, one of the engineers on this thread could explain this in a more scientific way.

Another factor is the Prius' engine has to run more often to deliver cabin heat.

Still, another reason for lower MPG, is air density. The ideal fuel/air mixture on a "standard" day, (at sea level 59*F/15*C), is around 15 parts air to 1 part fuel. Air is much denser with cold temperatures; i.e., more air molecules. Therefore, to produce the most efficient air/fuel mixture, the amount of fuel has to be increased in order to maintain that 15/1 air-fuel ratio. This is accomplished by the fuel injection computer. Hence, lower MPG.

 

That fact has been beaten to death over the past 13 years of Prius ownership... making it easy to not notice it missing in 1 of the 100's of threads all on the same topic.