Originally Posted by bobcat_ron
I need to update my GPS system for my truck, I need the ACTUAL fuel economy numbers for highway/city for a 2005 F450 Powerstroke, 325 hp and 570 ft/lbs torque 5 speed auto and middle range rear end gearing (what I mean by that is I had 3 options fo rear end gears, low was so low the RPM's on highway would be well over 2500+, high was so high I would blow my tranny, middle was perfect)
I don't want your numbers, I need the actual numbers as they would have appeared on the sticker on the side window.
I have searched for an hour and all I got was bullsh*t and reviews.
I need numbers.
There should be a sticker of sorts in/around the glovebox (if equipped) that states axle ratio. As you have the 450, I'll assume at a minimum either 4.10 or 4.30 gears are installed.
As for economy I can't see you doing much better than 15mpg highway (65mph) empty. 100% city driving I'd put it around 10-12mpg depending on the amount of lights, turns, etc. At least the 5 speed manual is more efficient overall than the automatic. Run synthetic fluid in the differential as it might lower friction enough to warrant a slight mileage improvement.
Only compare the duramax with similar tire size, axle ratio and GVWR. Comparing your 450 to a 3500 GM DMax isn't the way to do it.