I can't believe the figures reported are correct as it is showing 10 mpg for some short trips. Not even a truck with only an ICE would be that bad. This car isn't that big and even straight ICE ought to be giving better mileage than that. I have to think the software is just not accurate in these conditions.
I dunno, everyone's cars and circumstances are different, but if you've got bad conditions, I wouldn't be at all surprised if you could get it down to 10mpg. Plenty of other trucks and cars get at least that bad in bad circumstances. And the C-Max is not exactly a super efficient vehicle and WAY less so once it gets cold. Unless you've plugged off the front of your vehicle, from what i'm seeing, it basically only ever starts getting towards it's operating temperature going up hills. Once that's done it's pretty much cooling off again.
Sure, you CAN get some decent mileage out of it if you play around a lot with it and don't use any heat at all, but driving it at all like any normal person would, it's not going to be at the temp it should be and mileage tanks HUGELY.
For me I have about a 13 mile commute each way which is somewhat downhill in the morning and uphill back home. I've gone from a normal of getting to work on maybe battery only with maybe 45% left and then getting another maybe 3ish miles on electric on the way home before the engine kicks in to the last couple days where the battery is pretty much used up when I get to work in the morning and the gas engine has been running just about the whole time as well.