Make sure your transmission fluid isn't overfilled, it seems to suck up a decent amount of power if it is. The last time I filled mine was about four years ago, when the most I had done up to that point was changing the fuel/oil filters, so I was t3h suck and overfilled. After a drain/refill I've seen significantly higher mileage in relatively adverse conditions, so I'm pretty sure too much fluid in the tq converter can seriously hurt efficiency.