Topic: Questions about fuel economy/daily driveability

[Tr00b]

I just scored a new job...Money is alot better, but.... The good old commute is going to go from 30 min each way to 1 whole hour each way. I also lose my carpool... Going to be a dramatic change.

All I've got to drive is my Jeep 1997. Its pretty much stock except a spring lift (better than a budget boost) and 31" Cooper STT tires. It needs to have some work done to it but it still drives great and runs great. I'd love to pick up another car but if I can get ok fuel mileage out of it (20mpg or above) I'll just use it.

What is a reasonable expectation for fuel economy for a 4cyl Jeep? How much to my knobbies effect it and does it merit their removal? I know one thing, with the 31's its a total dog on the highway...

Does anyone else drive that far each day in their jeep?

[sharpxmen]

even all stock with 28'' tires you won't get 20mpg (maybe in a test all hwy if you drive constant speed at 40mph but otherwise forget it, real life scenario won't happen), any lift and bigger tires you add will keep cutting out of your gas mileage. I think brand new was rated at 18mpg (don't quote me though), but I owned 2 other Chrysler vehicles (not Jeep) and i can tell you that all the factory claims are complete b/s, in a daily driving situation will never happen. You'll find the odd guy claiming 24mpg with a 4 banger 'cause his gauge shown 3/4 tank and he drove 120 miles, you get the idea. If you want fuel economy look for a car with some shape that is not resembling a brick wall and smaller frontal area, the smaller the vehicle the better the mpg (and it goes for the newer the better at the same specs for engine size, weight and overall aerodinamic efficiency - weight comes in play more in city driving as compared to being aerodinamic is better at higher speeds like during hwy driving).

EDIT: found the factory when new mpg ratings, 16 city and 19 hwy (17 combined) http://www.fueleconomy.gov/feg/bymake/Jeep1993.shtml, but keep in mind that's new and all stock, not to mention the ideal scenario in which the test is conducted (get on the hwy, top up, drive constant speed at 50mph for 50 miles both ways, top up again and calculate the mpg, something like that). If you get 18 you're doing good.

[Jeffy]

When I was commuting around 45-1hr, I was getting 18-19mpg or so with 35's.  But then I was doing 65-70MPH in some areas, which is pretty fast.  Other times, I was sitting idle in traffic, wasting fuel.  I still think you'll be able to get into the 20's though.

[Tr00b]

I believe that the current mpg has got to be down around 14-16. The roads I drive are all fairly crapo, lots of hills, hard corners and other associated nonsense that I usually must stay in 4th the entire time to conquer, then a bunch of up and down hills on the highway. Also at least 1/3 of it is city driving. If I'm going to keep up with traffic on the highway portion 3rd gear and 5krpm is not out of the question at all. I used to get about 22-23 mpg with my Ford Ranger 4cyl 2wd.

The Jeep is fine at this point, but if I'm relying on it every day, I'll need to throw some money at some nagging things that are wearing out, I'd say if I need oem size tires too it'll be around $1000.

If getting ok fuel mileage is out of the question, I'll get some other buggy.

SharpX: I agree with you that the Jeep is a poor choice for fuel economy. Believe me. But I was wondering what people were truly experiencing.

Jeffy: Was your rig geared right etc with the 35's? Thats pretty darn good...

[sharpxmen]

SharpX: I agree with you that the Jeep is a poor choice for fuel economy. Believe me. But I was wondering what people were truly experiencing.

i'm getting 14.5 to 15mpg with 33s and 4.88, can probably get 16 in the summer if i'm light on the throttle.

[aw12345]

My yellow Jeep has been getting 16 mpg for years on 35" tires on mixed driving.
More than half city and mostly short commutes (5miles each way)
Just highway driving it will get around 18 depending on the speed I drive at.
Stock tires would be a good start should be able to find some 215/75/15 or whatever the stock size is cheap

[sharpxmen]

funny thing with manufacturer fuel "economy" ratings, very inconsistent from year to year
1992 4.0L 5spd manual: 15 city / 20 hwy (same for '91)
1993 4.0L 5spd manual: 15 city / 18 hwy
1994 4.0L 5spd manual: 14 city / 17 hwy (same for '95)
the '91-'92 is funny like hell
they're all the same so i have no idea how they come up with these ratingsa

1998 4.0L 5spd manual: 15 city / 19 hwy
2000 4.0L 5spd manual: 14 city / 18 hwy
2002 4.0L 5spd manual: 14 city / 17 hwy
2005 4.0L 6spd manual: 13 city / 17 hwy - you'd think this one should be better in the city with the 6spd

[grumpygy]

Well from what most say its right around 16 MPG and that is what I get on average.


http://4bangerjp.com/forums/index.php/topic,2827.0.html

[Jeffy]

Jeffy: Was your rig geared right etc with the 35's? Thats pretty darn good...

That's with 4.56's.  I did calculate my mileage out once with a 32's and stock gears to 26-27 mpg but that was all highway and speeds of 50-55mph.  All flat and used some drafting.  I think I can do better then when I had 35's since I'm running 33x10.5's now.  My city mileage is around 16-17 mpg.  Before I switch tires my city was 14-15 mpg.

2005 4.0L 6spd manual: 13 city / 17 hwy - you'd think this one should be better in the city with the 6spd

Well I believe the EPA does the testing and the Mfg. just posts that.  As for a 6-speed getting worse mileage in the city, it's typical.  You're shifting a lot more so that's a lot of wasted energy.  It's why hypermillers skip gears.  They'll go from 1st to 3rd so they won't have that extra shift.  IIRC, the 0-60 time for the  older Evo 9, the 5-speed is 0.1 or 0.2 seconds faster then the 6-speed.

[sharpxmen]

Well I believe the EPA does the testing and the Mfg. just posts that.  As for a 6-speed getting worse mileage in the city, it's typical.  You're shifting a lot more so that's a lot of wasted energy.  It's why hypermillers skip gears.  They'll go from 1st to 3rd so they won't have that extra shift.  IIRC, the 0-60 time for the  older Evo 9, the 5-speed is 0.1 or 0.2 seconds faster then the 6-speed.

i'm not sure how they do it but here's a good one: we were looking at replacing the Caliber (my wife's car) with something else, i picked up some brochures at the dealer and looking thru them i checked the liters/100km ratings (the metric equivalent for mpg but it goes backwards, the lower the better) and they also had the mpg ratings in there as well, somehow it seemed high for some of the vehicles (should have kept those, darn - can't remember which ones they were) so i converted the L/100km to mpg, were all off by about 5 mpg or so (higher and not lower) which is a LOT.
I still have the Chrysler 200 one which i picked a lot later, let me do the math - it says the Pentastar has 3.6ltr, 283HP/260ftlb and does 42mpg or 6.8L/100km on the hwy. If you convert 6.8L/100km comes to 34.6mpg, so how the hell they come up with 42mpg out of that, for 42mpg should be 5.6L/100km.
Same for the 2.4L 4cyl, 173HP fuel economy listed at 44mpg (geez, it's not a hybrid) or 6.4L/100km - again, converting 6.4L/100km to mpg gives you 36.8mpg, off by a big 7.2 miles per gallon.
Let me check the Chrysler website...
just did and there it says 20 city and 31 hwy, so in that case even the 6.8L/100km doesn't stand, if you conver 31 comes to about 7.7L/100km. so that's a big 11mpg comparing the claims in the flyer with the ones on their website (i wonder if that's regulated or something, dunno but it's a big difference)
EDIT: it's even worse, the 31mpg is for the 2.4L engine so the difference is 13mpg between the website and the brochure.

i don't know, but the Canadian mile seems to be a lot shorter than the US one, i wonder if they did km/gallon instead, i can take a picture of that page if anyone thinks it's b/s, can't believe they do that.
EDIT: 44/1.60934=27.34, so it's not km/gallon

(1 mile = 1.609344 km)
(1 gallon = 3.78541178 liters)

[Jeffy]

Well, I would guess that each country has their own version of the EPA and as such do their own testing.  Also does Canada use Imperial Gallons or US gallons?

[sharpxmen]

Well, I would guess that each country has their own version of the EPA and as such do their own testing.  Also does Canada use Imperial Gallons or US gallons?

liters, when you refer to gasoline then gallons it's US gallons especially when you talk mpg. Same for any container for gasoline or diesel, marketing gimmick i guess.

but looks like you're right they use Imperial gallons (i recalculated and 6.8L/100km is 41.5 Miles/Imperial Gallon) what they can come up with
although in this case they should use the nautical mile (1nautical mile = 1.852 km vs 1 mile = 1.609 km)

hang on a second, my Jeep gets 18mpg anyday now that i'm enlightened 

[sharpxmen]

just quickly checked the .ca sites for some brands
GM, Toyota, Honda/Acura, BMW, VW, Hyundai don't list the mpg for Canada only L/100km (which is the standard)
Kia does not list the fuel "economy" at all
Ford does the same as Chrysler using imperial gallons (Focus is listed at 59mpg)

[Tr00b]

What I was going to do to improve the economy was to run synthetics in the axles, trans and transfer case. Replace the U-joints I haven't replaced yet, fix all the shyt brakes and replace the unit hubs on the front. I'm afraid to run synthetic engine oil as I have some scabbed over oil leaks on the front cover and perhaps a rear main... I never have to add a drop of oil but don't want to start.

Then replace the 31's with sensible inexpensive road tires like these:

 http://www.tirerack.com/tires/tires.jsp?tireMake=Continental&tireModel=CrossContact+LX&partnum=175TR5CCLX&vehicleSearch=false&fromCompare1=yes

And put them on some on some alloy wheels from the J-yard or Craigslist to keep the weight down, unless I can find some nice take-offs.

It doesn't really feel good to pussify the Jeep, though...

[aka-justin]

It doesn't really feel good to pussify the Jeep, though...

Then don't.

My parents found an old camary for $300, and the thing gets 30+ mpg. Has good tires and hasn't left them stranded - yet. It's ugle but saves gas money.

Found one similar that's close to me for $600, http://inlandempire.craigslist.org/cto/3040469527.html