I know fuel mileage is always a topic for discussion with jeeps, so I just thought I'd pass this on.

My 2000 WJ 4.0 has 175K on it now and I bought it with 125K on it 4 years ago. The A/C doesn't work so we can leave that out of the picture. I've never driven to for more than 30 minutes to highway speed at any one time since I've owned it. I also never got better than 16.5 mpg average over a tankful of fuel in the last 50K miles. It has 3.55 gearing with 245/70R16 BFG Rugged Terrain tires on it and a torque converter clutch that doesn't work.

Okay, now I just 2 months ago replaced a cracked 0331 head complete with new valves and lifters. I just finished a 232 miles trip to Rochester and back on the NYS Thruway at 70 mph in 90* heat with all the windows down. That part of the state is just about as flat as Kansas because it runs thru the Montezuma National Wildlife Refuge which is a HUGE area of swampland. I tanked up just before starting out and when I returned, resetting the trip odometer so I'd know exactly how far I'd driven. Here's the stats;

232 miles, 11.362 gallons equaling 20.4 mpg! I was amazed and astounded! The wind was light and from the SW. The engine was running at 2100 rpm at 70 mph and I only drove about 30 miles at around 40 mph while in Rochester. I was using 87 octane E10 as usual.

I dunno, but 20 mpg seems astounding for a 15 year-old 4.0. I'm impressed. One other tidbit, I was watching the odometer trip the 1/10s corresponding exactly with the mile markers.

 

The best I ever got with my ZJ was almost 22mpg. A lot of that was downhill with a tailwind, also had stock tires and no lift. Now I'm lucky to get 15mpg with the larger tires. My JK is pulling in a consistent 18mpg in town! The 3.6 is rated at 285 horsepower and gets better mileage in a vehicle that weighs a thousand pounds more than my ZJ. Technology is amazing.

 

That's very good mpg for sure and I bet it would have gotten better with AC on and windows up.


I have never had mine on that long of highway only use at 70mph the most for mine on a freeway is only about 35mi. in 5 yrs. I run on 2 lane roads to the larger town's we go to about 50mi. away its shorter that way.


Thanks for the update that is closer to what I would have expected.