MPG gradually got worse over the years/miles. From 18 mpg down to about 14.2 mpg when I finally changed the spark plugs and coils as well as adding a K&N Air filter... Now the mpg won't go past 13.8.

My MPG has dropped significantly but no warning lights giving a clue to the problem.

was regularly getting 19MPG or better and now its down to ~13.8. Hard to pinpoint when it started but seems like it came on after the fuel sensor sending unit was fixed but not certain since mechanic isn't seeing any codes pointing to O2 sensors and fuel pressure is correct. Of course the mechanic made money for checking that out already. Debug costs are painfully annoying.