I was actually thinking that it might be off. I just filled up today and forgot to write down my mileage but I guess next week I will do it and figure it out.

 

I've just put almost 4300 miles on my 2001 4.7L over the past 2 weeks and did my best to check the MPG. It was almost all HWY miles at or above the posted limit and I averaged 15 to 16 loaded with kids and krapp (you know, that 200 lbs of stuff your kids feel they have to bring along on a trip).

Usually it's about 13 to 14 around town when I take it easy. One thing I must say, pulling the boat on the HWY or even around town SUCKS the gas down for sure. I've had it as low as 10 MPG (with OD off and running 65/70).

 

I did the math manually to compare to the computer display and it's funny. Some filler's the display is almost accurate, some fillerups, the display is nearly 1.5 miles off to the negative so that's a plus for me.

When the display is off, it is off in the minus range. Meaning if it says 11.5, then I do the math after fillup, I actually was getting 12.0-12.5 when I am slapping the gas pedal. When I baby the pedal the display shows 12.1, I actually got 12.7-13.5. Go figure. Seems when the display shows a higher number in city or highway figures, it is more accurate, when it shows a lower number, it can be off.

And I compared these figures using the same daily driving habits. Babying the pedal for 2-3 tanks. Then moderately play hard on the pedal for the next 3 tanks.

So my conclusion is if you baby it, the display will show a better accurate reading. If you play rough or gunning the pedal everywhere, the display will be off but at off to the minus side thank god.

 

I always laugh when I see posts questioning MPG with the D. Like someone said before, it is a gas hog, just love it for its good points and learn to live with it. I mean heck I can't blame ya, I posted the same awhile back when I was new to the forum. Glad that I found out it wasn't just me.

about 13 city and 15-17 hwy

PS - It depends how you drive. I know this is a given with any vehicle but it is essential with the D.