I have a 2004 fx4 4x4 5.4
Use to do 700 to 750 km half city, half highway.
Since the past 2 months I do about 625 to 660 km.
Did not change my driving .

?????????????

 

make sure your tire pressure is correct......noticed mine were 5lbs off with the change in weather.

 

it could be that your area is now using the "winter blend" fuel. I live in Chicago area and they have used it for about 6 weeks now. Every car I have ever owned does this in the winter. Gas prices go up, mileage goes down.

 

I have also noticed that the winter blend does not affect mileage as much a cold weather. I make trips in July, October and February each year. The mileage remains pretty consisent on each trip, so the blend does not affect mileage much. However I only drive 4 miles to work each day. In the summer I average 2-3 mpg more than the winter, and it gets worse the colder it is.

Remember when vehicles had chokes, they ran a little closed until the engine warmed up, a little rich. Just because the engines are fuel injected they still need to be a little rich when cold, a little rich means worse gas mileage.