I am looking to buy a YJ w/ the 4.0L and I have heard a wide variance in average MPG from people. So you all help me out and settle this. If you could post your year, average mpg to date, and current mileage that would be awesome. I do plan on modifying the YJ so those number count too.

98 w/4.0, 5- speed, 4.88 gears, 36" tires, and 13-14mpg

92 on 33's 4.0 3.54 about the same 13-15 if I'm lucky..not sure why you need to know but don't get one if your looking for economy..

My crawler, 37" tires, 4:10 gears, T-18 and a 258 gets 12ish. You are about to make a big mistake if you are going to buy a jeep and hope it gets good gas mileage. Anything modified will most likely see less then 15mpg. Only stockers as a whole get anything higher, even the highests ive seen i 20 mpg or so with the right setup and highway driving.

138,500 miles on a 92 YJ, 5-speed, 33's and 4.56s. 14-16 mpg

89 w 350 5.13s gets 10 :)

88 w/ 258, Peugeot ba10, 32s and 3.07s :eek: :( - 16-17mpg

Fuel economy's about the only thing the 3.07s are good for.

around 14 if I stay out of the boost

around 8 when im in the boost

1993 stock 4.0 turbocharged running 5.5 pounds of boost, ax-15, 5.38's, 36" tires for street driving, 40" maxxis CC's for the trails

Why are you guys getting such crappy mileage? Before I changed a bunch of things, I was getting 21mpg HWY with a carbed 258 on 33x12.50s. That was with a 3 speed.

I figure with fuel injection and a 5 speed you should be able to beat that.

Is a CJ5 that much ligher?
________
Arrya (http://www.girlcamfriend.com/cam/Arrya/)

Why are you guys getting such crappy mileage? Before I changed a bunch of things, I was getting 21mpg HWY with a carbed 258 on 33x12.50s. That was with a 3 speed.

I figure with fuel injection and a 5 speed you should be able to beat that.

Is a CJ5 that much ligher?


Were you going downhill?

probably downhlil and with the wind helping :)

Honest to god 21mpg on the HWY over varied terrain (couple east coast mts). Did that for multiple tanks over the whole trip. The mileage was measured on a 2004 Toyota Corolla that I was following. I had them keep track of the mileage because my fuel gauge doesn't work and I don't trust the odometer. The tires were Dunlop Rover Ats. They are really shitty tires, but they are light and apparently have low rolling resistance.

79 CJ5 with stock 258, MC2100 1.08 46 jets, 9.5 pv, GM HEI
T150/D20 D30/AMC20 Stock gears (probably 3.37 or so)
Doing a slow and steady 55 mph.
21 mpg no kidding.

Probably doesn't do that anymore after some mods. Fuel is also shit now a days.
________
COLORADO MEDICAL MARIJUANA (http://colorado.dispensaries.org/)

i was able to get 16 or so when i had my rig on 33s. But i never drove faster than 55 on the freeway. Jeeps are square, not good for fuel economy. My jeep is also a hardtop. With the top off mileage drops a bit. But then again i have a 4.2L and not a 4.0 last owner changed some stuff in the motor so it has more torque.

My best was top down and loaded up with stuff for senior week. 3.07's and 30's with the 4.0. All highway. Now I have 33's and 4.10's and get 15 pretty much no matter what kind of driving, highway or city.

More spec's than you'd need in my sig , but I basically concur , 15ish MPG reguardless of driving style .

I try to even out the average by putting as many miles as I can on my sportbike , scull-crushing acceleration @ 46 MPG :)

FWIW...
4.0, 5 sp, 4.56's on 35's = 15 avg.

93 4.0 ax-15 4.10s 33s 22 mpg:flipoff2:

94 4.0 ax-15 4.10 285/70r17 bfg mt's. Magnaflow 2.5' catback. high flow cat. Rock-it intake. 19-21 hwy. last full tank 18.6 gallons 355 miles on od. Keep RPM's under 2500....

'89 4.2 with electric fan, ax-15, dana 44's, 4.88's, and 37" mt/r's right at 13.5 mpg.

1991 YJ 4.0 HO with 195k on it, 5spd, 4.10s, 35inch Krawlers and I could get 14-15 mixed driving.

93 4.0 HO, Auto. 35x12.50's. 4.88's, 8.8 out back, and lockers front and rear. 10 MPG on average.:laughing:

4.0, Auto, 4.10 On 35's, Header, About 12 Mpg

92 yj 4.0 4.88s 35 inch krawlers mixed driving about 16 to 17 belive it or not lol
:laughing:

94 YJ 4.0 ax15 Dana 44 front, 9 inch rear 4.10 gears 35" procomp tires. I get 16 MPG around town. I've yet to run a full tank on the highway with this set up but I drove about half a tank on the highway and the other half around town and when I filled up and calculated the MPG was 21, so my highway mileage is over 21. I think the locking hubs really help out my highway mileage

Stock 94 YJ 6cyl, 5spd on 30x9.5's 22 (highway w/sticking caliper) 20 (city/highway) and 16-17 (city).... beats my old muscle car by more than double

91 4.0HO, Auto 4speed, 3.95's, 35x12.5's Always mixed terrain more low gears than highway.

Now, with the cracked header and hardtop/full doors 12.58mpg
Before with good header, softop and 1/2doors 14mpg.

Thanks for all your posts on this subject. I am not buying a YJ strictly on economy. I was just curious, started asking around and got a huge range on answers. basically same thing i got from all of you. If you leave it stock and don't hot rod it you can get 20-22 mpg. but with modifications and trail use the mpg's start decreasing. I plan on getting a YJ, and put a set of 30x9.50's on then calling it a day. Till I can afford to shorten the tubes on my f/r 60's and stuff my mopar 408 stroker motor in it. Then the mpg's will be around 8. I will definitely be posting that build. again thanks for all the responses

I think a good bit of it has to do with how people drive. Some people just hit the brakes and gas more. I've always gotten better fuel mileage out of my vehicles than most other people can get out of theirs.
________
Krystal19 (http://www.girlcamfriend.com/cam/Krystal19/)

Update Just filled up. 17.489 gallons. 305 miles on OD, thats 17.15 MPG. My wife drove the rig for 2 days. She has a lead foot. Driving Habits have a lot to do with MPG's.....

Stock 95 YJ 4cyl, 5spd on 33x9.5's 15 (highway) 11 (city/highway).

Hopefully doing an engine swap this summer to remedy this issue.
I must say though that if I had a 4.0 to begin with the engine swap would probably be much easier (as you can keep the AX15 tranny for most applications).

lt1,auto,38.5's,5.38 gears. 9mpg avg.

i have a CJ7 which is close enough.
4.2 MPI/T-18/35's/4.56 gears- 18 MPG driving carefully(which i always do)-this is in the mountains so not a great estimate

2.5 4pooper 5.38 gears and 37 boggers ill get 14mpg average. and still do 70mph

Drove the Jeep from Cincinnati to Indianapolis yesterday. The combination of a 5.0, ford racing B303 cam, 4.56 gears, AOD and 37 tires is not quite right. Feels a little under-geared. It would probably be happier at 65 with stock mustang cam, 5.13s or 35s.

All in all I was very happy with my first road trip since the drivetrain/engine swap. I had put about 600 miles on it over the last year and a half driving around town tracking down little bugs here and there. I put about 400 miles on it total yesterday. I averaged 14.6 mpg on the first tank going to Indy. I kept it about 65 and followed a big rig for about 60 miles. On the way home I drove about 70mph and got 12.8 mpg. Not too bad for a heavy, big tired honkin brick. This is better than my stock 2001 Ram 2500 V10 4x4.

I've tried 87, 89 and 93 octane gas. It pings a little under load with 87 but runs fine on 89.

So..1995 YJ, 5.0 .030 over, 10.5-1 compression, GT-40P heads, AOD transmission, Atlas T-case, 37" Krawlers, D60 front, 9" rear. 4.56 gears.

Thanks for all your posts on this subject. I am not buying a YJ strictly on economy. I was just curious, started asking around and got a huge range on answers. basically same thing i got from all of you. If you leave it stock and don't hot rod it you can get 20-22 mpg. but with modifications and trail use the mpg's start decreasing. I plan on getting a YJ, and put a set of 30x9.50's on then calling it a day. Till I can afford to shorten the tubes on my f/r 60's and stuff my mopar 408 stroker motor in it. Then the mpg's will be around 8. I will definitely be posting that build. again thanks for all the responses



Yeah man, I was in the same boat as you... kinda... I have and drove a 1969 GTO as an everyday driver then i bought my 94 YJ with a 6cyl for gas milage and I am getting better than 22 mpg on the highway. I plan on puttin 31x10.5's under it in the next month or two and I dont expect much of any drop in mpg's

1993 yj 4.0 H.O 37s 4.56s getin about 10-12 if lucky thats like me going going down hill