Ok crazy question here. I have a base sasquatch. For the first 2000 miles I was getting about 16.7 mpg in normal mode. I switched over to ECO and it went up to almost 18mpg...for a short time. I've kept it in ECO mode and now it's down to 14.8 mpg. Nothing has changed driving-wise other than the mode - and I'm up to 2800 miles now. Any explanations?