I have noticed i am getting lower and lower fuel mileage out a gallon of 91 octane (as required for this year engine) gas now it's right around 7 MPG and that's about it.
You should be getting double that mileage and you mention you've noticed it getting worse. I would do some investigating like making sure a brake isn't hanging up or do a plug reading to see if it's overly rich for some reason. Either could be a reason for no CLE.
