Take it out on the highway on a level stretch (as level as possible, not in the mountains) and lock the cruise control at 60 or 65. Reset the average mileage on the DIC and run it for 10 miles or so. If you get better than 20 at 65 you're doing good....
The Constitution needs to be re-read, not re-written!
If you can't handle Dr. Seuss, how will you handle real life?
Current oil burners: MB GLK250 BlueTEC, John Deere X758
New ride: MB GLS450 - most stately
Gone but not forgotten: '87 F350 7.3, '93 C2500 6.5, '95 K2500 6.5, '06 K2500HD 6.6, '90 MB 350SDL, Kubota 7510