I looked on the parts list I have and could not
see it and as I am out of town until tomorrow
possibly someone else can look.
I believe it is an external drain located
on the right side and draining just in front
of the passenger door, could be wrong tho.
I would suggest the air intake/cowl drain is plugged therefore
snow melting at the windshield/roof levels are building up
under the cowl and overflowing.
I have played with this also and believe the method by which the figure
is derived is immediate at reset but more accurate long term if you leave
it alone.
Try resetting it then accelerating hard immediately after and watch mpg
go into the crapper , then let up to say 40 - 50 mph for a short drive and
you can see it averaging out.
I don't know what components are fed to the algorithm that that determines
display/figures but it would be interesting to have explained.
If the OE battery is marginal then poor electrical continuity (corrosion)
will and has in my personal experience caused weird electrical faults ,
if it's the original (possibly 2009 install) then this could be early sign
of battery failure.
When talking AWD between different car makers it's apples and oranges.
Some are bullet proof and others are marketing tools that work in a simplistic
fashion , you can't compare a Dodge to a Mercedes,Audi or Subaru.
Welcome to the forum .
I am sure questions will come as you drive it for a while - that's why we have mutual interest
in helping each other , no question is dumb.
The key in the fob is only used to open the doors manually and lock the glovebox.
If you have the push button start the fob has an IR chip in the end opposite to
the key location and although I have not tried it supposedly pushing the start
button with that end the chip will be recognized and the start sequence will work.
This would only be required if the fob was dead as in battery failure.
I did not think the CVP had push button start but used the pre 2011 usb appearing
fob/key assembly.
The other fusebox is located up and to the right side behind the glovebox.
I would suggest that you may have a broken wire(s) in the flexible loom between
the cabin and the tailgate.
This site gives diagrams/schematics for modern Chrysler products.
https://techauthorityonlinedemo.extra.chrysler.com/service/repair/wiring/view/classic.htm