What you post seems kind of steep for a drop off with that many miles on the tank? Are you sure you didn't hit the trip meter to B or something. I notice that with my driving style my first 100 miles on the each tank generally sucks as job is only about 10 minutes or less from where I live. When traffic is right during rush hour on the freeway and late at night is generally when I kill the EPA numbers. I wouldn't worry about it to much the most I have seen my displayed off by was 4.5mpg after calculating. Not sure what happened but, I have never seen it off by that much again.

James


Best MPG tank: 57.7 calculated
Best Trip: 73.8mpg displayed(Palmdale"LACR" to LAX)