Most things I know of to affect mpg would cause the CEL to light up.
TCC solenoid or ignition issues, timing chain and such.

 

Did somebody forget to release the E-brake? Don't laugh, done that.

 

Good point, I’ve had eBrake cables cease up and not release causing drag on the drums and shoes. So, that’s worth investigating.

 

My car went from 24-25 city to 14-15 when the timing chain was going south but now it’s struggling to recover and is currently at 18-19 city. I replaced the chains about 3 weeks ago now.

 

I guess the OP isn’t coming back to his thread.

After rereading his posts I see that he wasn’t looking for actual help. He was only asking if anyone else had issues with low gas mileage.

 

The responses are all good and fireman covered all the bases.
I forgot about the reset of the avg mpg. That number could stay low for many miles if there is bad data (lower than actual) in the algorithm for the system to average out.
As I recall the DIC mpg was always a bit lower than the pencil and paper calulations when I was comparing the two in a 2.2L '08.
When reset to zero each fill-up.

Oh well either way it will get them safely where they are going today