Do you get about 4 MPG less during winter ?

[enkid]

I get about 8 to 10 MPG worse in the winter on average
sometimes more, sometimes less

Longer warm up time
Winter formula fuel
Rolling resistance of tires worse when cold
More wind, more rain and snow

[paraganek]

thank you guys for sharing, it makes sense to me now

[Yaris Hilton]

Originally Posted by enkid

Rolling resistance of tires worse when cold

That was impressively demonstrated by the old-fashioned nylon 6-ply bias tires I had on my 1940 Ford. When left sitting for a while, the cords would take a set and "flat spot," which would smooth out after rolling for a while. In cold weather, I'd go thumping down the road on flat spotted tires for quite a while. Modern tire cord materials don't set that dramatically, but they still stiffen up quite a bit. As do the rubbers used in the tread and carcass of the tire.