Same here. Keep it a 65 on the Hwy and the mileage is 13-15. Push it over 70 and it drops to 9-10. I have a 108 mile round trip commute and most of it is highway. RPM makes a big difference.

 

Feeling good if I get above 11. Speed and short trips can put it below 10. Have oversize tires and full roof rack which I know impacts it. I didn’t buy it for its gas mileage

 

The one time my mileage really dropped was when I was running cruise control with a heavy load trying to keep 110-120km/h with some hills AND slack in my cruise cables. It was running too big a”space” between acceleration and deceleration so it did both. A lot.
Took me a while and a scary fast half a tank to figure it out.

Check the cables and tighten them up to the rave specs. I do it about every 18 months. Well worth the time.

 

Multiple trucks, typically run 16-17mpg running 75 mph in the foothills of the blue ridge between VA and SC. One of my trucks does not have functioning 02s and it still pulls 17 mpg. Bone stock on michelins with bypass stat and pcv mod.

 

With all the stuff I have done I cant believe I get this crappy gas mileage. FML.

 

I think that getting 9-10 MPG in city stop-and-go driving is not so unusual, especially if you try to keep up with nimbler cars. I usually get ~14 mpg in my mix of 80% highway and 20% city driving, and I've gotten 16 mpg at 70-75 mph freeway cruising, and 12 mpg towing a loaded 3500 lb. horse trailer. Aerodynamics are a big factor too: I've had a gain of 2 mpg with a tailwind in our old RRC versus going into the headwind the other direction. The RRC is a rolling garden shed, and the Disco is worse with its high roofline that steps up progressively toward the tail.

As has been mentioned, the biggest variable is the driver, but tires with low inflation pressures have a staggering effect, as do oversize off-road tires. Nobody has mentioned tires or pressures, so that's an open question.

Scott

 

something is definitely wrong with your rig there. Your eating 50 % more fuel than you should. I would think you would notice something going on engine sluggish? Exhaust smell. ?

 

Fuel economy.gov has it at 11/14 for a stock truck avg 12. I think if you compare a similar weight full-time 4x4 with a 1990’s technology V8 engine you’ll see similar results

 

Hell I have rented SUV's from enterprise in the last 4 years that did not do any better than 16-17. Nissan Pathfinder for one

 

I don’t smell anything at all. Engine idles and runs great. Not sluggish at all. Fuel maps are good.