265 75 16s on my 5.2, in 4wd I get about 10mpg on the highway. If you're hoping for 11mpg then you already got a realistic expectation

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My 95 4WD 5.2 all stock gets about 16 mpg which is a mix of highway and city driving.

 

I got about 13 with my 31's.

Much worse than that now.

 

Stock tires. 14 City, 16-17 Hwy.

 

... Man I'm glad all you guys are one up on my expectations. Maybe I'll not be disappointed when I get my New2Me 5.2 back on the road.
I drive my daily driver 150 miles a Work Week... WEEKENDS MAY BE 0 & OTHERS MAY DOUBLE THAT.. So I'm not worried about it's mileage .. Since I live in a small town & It's only 10 miles to work. Not a big issue.
But weekends could be 300 mile trips.
I'm a big driver.. I deliver parts now & One day I may drive 500 miles & the next I may only drive 160 miles.. So a 300 mile drive on my weekend is a piece of cake.

 

245/70/16, that's 30 ish according to my son.

If I drive like a lead-footed teenager, I get 11-12 mpg in traffic. If I spend more time on the freeways and drive at reasonable speeds, 14 - 16 mpg.

5.2L 98 ZJ coming up on 190k miles

bob k6rtm

 

I do a LOT of highway driving; going the limit. Running 235/75/15 tires, NP242 in FT (or 2wd, same MPG, btw). I get around 15-20MPG on the highway based on the 'instant' mpg reading, and I have averaged around 14-15MPG over the course of about 5000km.

EDIT: forgot; this is my 94 5.2L 46RH. Only about a 1" spacer lift.

 

265/70/16 with 2" of lift. Where I live is all stop and go theres redlights and stop signs every few block so Im lucky to break 10 in the city honestly.

 

96 stock with 245/75/16s get an avarage on the hud of 15mpg.

50 miles round trip to work half hwy half back country hilly twisters.

 

98 5.2 w/265k miles, 245/75/16 Duratrac tires and I 15/16 city and 18/20 highway on long trips. GPS and speedometer checked. I'll bet most of the lower mileage posted here is a misreading due to the speedo gear being incorrect for the tire size causing a mileage misread.

 

'98 5.9, 4.56 gears, 33 x 12.50 Cooper Discoverer STTs, and 285/75 R16 BFG AT Ko2s being used. 3.5" lift, weight measured @ 4700lbs.

Average mileage doing 50/50 city/ highway has been ~13.5-14MPG for the past six years my niner has been modified.
We did a 1000+ mile roadtrip with my wife and small girl 1.5 years ago - mostly highways & some city driving. Both flat land and mountaneous regions. Speed limits between 45mph...75mph.
Based on fuel fill-ups and GPS- verified route length, average consumption for the whole trip was 15.7mpg


I sure don't drive slow, but I do try to drive smart. That is, accelerate reasonably quickly and then let the Jeep shift into highest possible gear. I try to make sure the TC lockup stays engaged as much as possible. And the other normal crap of what you need to do trying to save a bit on fuel bills.. fuel costs a lot here in Europe
I know of people driving similar ZJs with a 4.0, who drive like a grandma - getting worse mileage as I do with the niner.

 

10mpg city, but traffic here sucks, I'm mostly in 2nd gear.

 

Yeap.. purely city driving in slow stop-and-go traffic will certainly result in something like 9-10mpg.

At times, I've wondered how would these do with cylinder deactivation and a modern 9-speed auto tranny Considering a stock 5.9 will do 0-60 in 7.0 seconds with an inefficient 4-speed, a 5.2 with a modern 9-speed would probably beat that by a second - having about 4mpg better average mileage :laugh:

 

I wonder how this engine would do with a 5 speed manual transmission.

 

My 97 5.2 with 30x9.5 tires gets 13-14 MPG 50/50 city highway. 231 T case, and that's with an extremely heavy foot.

 

my first one zj was completely stock. it got 16-17 mpg in the city and 18-20mph on the highway if I added marvel's mystery oil. My second ZJ had 31" tires and was like 13" wide. It got like 11 in the city and 16 mpg on the high. Marvel's Mystery oil didn't even help.

 

Wow you Guys are encouraging. I really felt like Most would say 9 too 11.
I sure want this V8 too step up & take the place of my other ZJ . My 6cyl just has more issues than I care to work on. I like it but I just can't seem to get ahead it it.

 

ZJAY98 What does the Marvel Mystery oil do for the gas mileage.I thought it was just a cyl lubricant. Do you feel it works better than Lucus... I've used all the gas treatments as I owned a parts store for 30 years. Too me Marvel did one job while Lucus was more to fuel mileage.

 

Totally stock 95 5.2 with 30" tires, driven 1 mile each way to work by my wife. Getting about 9 mpg in that scenario. Out on the freeway taking it easy...over 17 mpg. It does have an ignition upgrade...MSD coil, iridium plugs and 7.5 mm cables. And 2wd with the 242 TC.

 

1994 5.2 FULL TIME 4X4. I used to average 12 per tank with a mix of freeway and street driving. Recently did a full tune up and ore bumped up to 14! Big difference between 55 mph and 75 mph on the freeway too, like 21 mpg vs. 16 mpg. I'm old now and so is my jeep, so i keep it in the slow lane under 60.

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My 98 ZJ is stock, and i get maybe 18 mpg mixed highway/city

 

Just came off a 2500 mile road trip out east multi city friends and family round trip. 249 t-case. Running brand new Firestone AT 235 75 15 tires. I also ran the speed limit, cruise control saw heavy action. I manually tracked the trip. The trip meter also gave the same result. I got exactly 15mpg for the total trip. Mixed metro Denver driving drops it to 11ish mpg.

 

A 5.2 redesigned modern EFI could be getting easily 400+ ponies. That and a modern trans would do amazing things.

I wouldn't buy one, cause it'd be a computer mess, but it would be cool to see an updated ZJ.

 

Somebody should try it. Install a complete modern engine/trans. New 8/9/10 speed transmission. It would be a nightmare to get it swapped in though.

 

SO my 4.0L is still down at 11.5 to 12 .
& I've not gotten my 5.2 going yet it's close, Just not there due to shortage of money. I ended up putting 30x9:50R15's knobby s on it . I've got my heater working finally but I'm in need of ''just'' an AC clutch hub or shoe .. I ordered on from ebay but it's not shown up in 4 weeks & I've got my compressor apart. So I can't move it until I get it back together. I'm sure ready to get it on the road.

 

95 5.2 zj. With the all time 4x4 and 32" mud tires i average around 11 with premium grade fuel, and about 9.5 with regular unleaded

 

Dunno why you would loose 1.5mpg running lower octane fuel, because the amount of energy in the gasoline doesn't change with it's octane rating.
Only thing octane rating does is high octane fuel reduces the risk of detonation/ ping/ knock.
Our Jeeps don't even have knock sensors, so the PCM cannot adjust for knock. So if you do not get detonation/ ping/ knock, higher octane fuel won't do you any good.