I see this every winter in Ohio,customers start complaining about poor fuel economy and longer crank times when starting. The thermostat stays closed longer not letting some of the sensors see the hot water like they did in warmer weather. The fuel trim stays rich longer and you will burn more fuel.
Now about that fuel in Ohio In most counties they add more alcohol to the fuel in winter and thus your fuel consumption goes up when your A/F sensor sees a lean condition and adds more fuel until it's happy your engine isn't going going lean.
That's just my guess

Gus