I live in Colorado. One cold morning the CEL came on. Dont remember the code, but it had to do with engine no getting up to temp. I changed the thermostat with an OEM Ford T-stat. The Ford parts person couldnt tell me the Temp rating, only that it was 3 revisions newer than the one I had. The spring in the T-stat was much stiffer. Anyhow, after changing it, I gained 3 MPG! In the winter I could only get 24 MPG. I figured it was a combination of winter blend fuel and letting the car idle to watm ot up. The rest of the winter, I now average 27+ MPG and still let it warm up. The warm up is for my own comfort.

Anyhow, just thought I would share. Car heats up much faster now to

 

You don't realize how much difference the stat makes until you change yours. My FEH was sitting on 24 mpg when I bought it, which disappointed me. Changing the stat helped the most, then the rear A/C door motor, then raising tire pressure to 45 psi. Now I can get 30+ mpg pretty reliably over multiple tankfuls.

 

I usually run recommended air prrssure while I have on the snow tires. The tread is so soft, I try to maximize tire life.

Came to Albuquerqueast this past week and only got 30mpg. This was maintaining 70-75 MPH, some headwind for a portion of the trip and normal tire pressue.

gonna put the air up at 40 for the return trip today. This is a 400 mile trip.

Thanks for the reminder about the air pressure. That will help with my trip home today.

 

I had huge issues with fuel economy on my 08 FEH. I also got a CEL, P0128 if I recall which triggered me to check my coolant temp. I wasn't able to get my engine above 161f. Picked up a new tstat off amazon rated at 194f, installed it with my father-in-law (no small task, let me tell ya!!) and my MPG has gone way up, I go into EV even below zero and it just seems to run sooo much better now.