yellocoyote
Administrator
I was referring to the confines of pavement in this case...
Otherwise, you are correct sir. 
Mileage/RPM/MPH Question
- Thread starter Jeepin05
- Start date
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I was referring to the confines of pavement in this case...
Otherwise, you are correct sir. stevebaz
New Member
The cheapest way to find out is with a good vacuum guage with a large calibrated dial. The higher vacuum reading you keep on the guage the better the milage you get. There is a problem with speed and air resistance and once you cross the threshould your vacuum reading will drop drasticly as your engine tries to add more fuel to matain speed. In the old days with very un areodynamic cars that threshold was 55 mph which is where the epa matained mpg testing at and later enforced the national speed limit at. Depending on the aerodynamics of modern cars and the much more power efficient engines these days some of that speed has moved up a bit. If you can the test data with the epa on the liberty you can see just where they tested it.
Steve
Steve
Andynator
Full Access Member
ineedabouttreefiddy
Full Access Member
75 works for me. Just ease into it and keep it steady
dude1116
Full Access Member
Well isn't this an interesting thread to get dug up? I'm surprised to hear such high numbers. I'd say mine behaves the best at 70. Driving 55 around town (In a 45...there are NO cops on the road I do it on. Thank gosh.) Generally will get me 17-18mpg average. Driving 65-75 on my way home from school (with lots of traffic lights... p Will usually nab me the upper range: 18-20mpg.
p Will usually nab me the upper range: 18-20mpg.
Akedos
Full Access Member
Well since this thread was brought back... I'm currently experimenting myself. I got around 18-19 mpg while traveling around 73-75mph on the highway about 40-50 miles daily plus some light city miles. I'm slowed it down for the last two tanks and am going to see what 65 mph gives me. though I do have a stick shift and no lift so I expect better numbers than some of you.
Snail Farmer
Full Access Member
I have a manual in mine also. I drive 20 miles to work. I've found I get the best mileage at 65. I average 23-24 mpg. If I do 70-75 it drops off to about 19 mpg. I live in a pretty small town. The speed limit everywhere is 30, and heavily patrolled by cops, so I can't really get away with speeding through town. But town driving at 30 I average about 14 mpg. My engine is stock, I haven't done a lift yet, and I'm running GY Wrangler Silent Armor 235/70R16's
Whenever I have to drive that slow I disable OD, because it is a ridiculous slug at that speed and the POS programming in that trans tried to get it into OD as fast as machinely possible.
Snail Farmer
Full Access Member
Naw I have a 5-speed. I hate automatics
jeepsterkj
Full Access Member
This old thread popped up during a web search, and again I was surprised that so many US KJ owners were happy with such high fuel consumption figures...17-19mpg being average for a 3.7 Petrol with an auto box...My 2.8 CRD with 6 speed manual box averages 32 US mpg but it can average 36 US mpg if I drive like a granny...That is 45 UK mpg!...So if you want to save money on fuel, the solution is to get a CRD.
turblediesel
memberable
Or not. Best my US CRD ever got was 25 mpg for one tank driving across the country. I think I just lucked into better than average fuel for that tank. Normal was 23 mpg in 2wd and 19 mpg in 4wd. that was before the dealer's F27 reprogram when the numbers dropped to 19 mpg in 2wd and 14 mpg in 4wd.
Add in all the mods required to keep the engine in one piece and any advantages of a CRD evaporate.
Diesel still costs more than gasoline here so, no savings there.
Differences in fuel quality between the US and Europe probably account for mpg differences.
