Hmmm..I may look into the software update issue. The car was such an amazing deal ($12,500 for 2013 SE with Pano roof, 32K miles, 1 yr bummer to bumper warranty--i thought it was an amazing price) from the dealer because it was a lemon buy-back due to the software issue. The sheet i signed had a list of software updates that had been performed. How do I determine if they were done correctly? All the paperwork I have indicates the problem was fixed...is there a way to verify, or check which software version is currently installed?
Turning the heat OFF I'm getting 33mpg, which i still feel is low, but some people seem to think that's a winter normal mpg, so I don't know. Also, oddly, the vents seem to be mostly closed--black plastic louvers maybe, so i feel like there's nothing left to do, unless people are blocking 100% of the vents? The car was in California, and its lifetime MPG is 40.
What was the "lemon" problem? What does the paperwork say was done? Did the car have the "No Start" issue due to the 12 V battery being discharged by a parasitic load on the battery. Ford did issue Field Service Action 15B04 for this issue which addressed several possible causes and updated software. However, this though does not have anything to do with FE. It does seem that the number / frequency of this issue has declined since this FSA.
There was a FSA 15B03 for software updates to improve FE, IIRC in 2013. It included better operation of the shutters and ICE during cold weather. I believe some had issues with this install in that it didn't install correctly (IIRC, it was something to do with the way the software was downloaded from Ford). But it's unlikely that this is an issue with your car as there have many many software updates since which would be the latest version (and include previous updates). You can get on etis.ford.com or owner.ford.com and look at any outstanding FSAs items for your car. The items are removed when the dealer completes the action. So, if there is nothing showing, then all related items for your car have been completed.
I don't block the upper grille as that is the air intake for the engine. But some do / have blocked the upper grille so that the intake air is drawn from the engine bay area which should be warmer than the ambient air temperature.
Also, I doubt the latest Fit would get better FE than the C-Max in the city / suburbs. Fuelly.com shows the Fit to be around 34 /36 mpg overall. Fuelly shows the 2013 C-Max is around 39 / 40 mpg.