No doubt it's both winter gas and warming it up. There is no reason to warm the engine, unless you're remote starting to get heat, and in that gas you're going to noticeably impact your MPG unless you drive a lot (which will make the startup less noticeable in the scheme of things).

winter gas and a new air filter will kill MPGs. I noticed after i changed my air filter my fuel mileage dropped for about 500-1k miles or so, and then went back to normal. I average around 17mpgs in my ecoboost (drive a minimum of 62 miles every day). Right now i am averaging around 16.5 in my last two tanks since getting the 70k mile service at the dealership, which is also right around when winter gas started coming out as well.

The air filter thing is odd, though, I have to admit, mine did drop as well after I had the filter replaced.

I used to have a 2012 EB, it got well below expected MPG since I was coming from a 2010 Flex that was also EB and got 20+ MPG, I expected 18, got 14, dash said 17. Took it in and complained that it was getting no where near expected MPG for the combination. Ford said run Premium and your MPG will improve.

Yeah

Right

did it anyway.

Got 18+ MPG after that :eek:

Being that winter blend is out, weather is colder, and you remote start(EB like to drink gas when idling), all account for the drop in MPG. You may want to try a couple tanks of Premium and see what happens.

Echoing the other responses, in my personal opinion of importance in regard to this thread:

1) Idling to warm up kills MPG's.
2) Winter fuel hurts economy on the 3.5 ecoboost
3) Change your spark plugs every 30k miles.
4) Keep a clean air filter in there. Make sure you get a good seal when you replace it.