The biggest reason for increased fuel consumption is more fuel used at start up in cold weather and more fuel used to heat and maintain operating temperature of the engine plus your drawing heat from the engine to warm the cabin of the car. All that is paid for with increased fuel consumption. All the other reasons mentioned add to the increase but over coming the cold engine is the main one.
FoMoCo cars I've owned
1970 429 Cyclone, 1978 LTD II 302, 1980 Fiesta 2nd best Ford I've owned
1986 Tempo LX, 1990 Areostar,1996 Areostar Best vehicle I've ever owned
2005 Ford 500, 2006 Freestyle, 2012 Focus Titanium pearl white