Gas mileage

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Jan 31, 2009
As the fairly new owner of an ’04 UZJ100, I did some searches of this forum for collective wisdom on improving gas mileage in the 100 series. I also searched independent (non-manufacturer) web sites for detailed information. Disagreements about what helps and what doesn’t help are common, but there are some things that seem to make a difference.

The U.S. Dept. of Energy, U.S. Environmental Protection Agency, and Consumers Reports have 14 actions and the respective mpg improvements (or not) on their web sites:

1. Careful driving instead of aggressive driving: up to 33% improvement
2. Driving the speed limit instead of faster: up to 23% improvement
3. Turning engine off if idle time will be more than 2 minutes: up to 19% improvement
4. Maintaining the engine and vehicle: up to 4% improvement
5. Removing excess stuff carried: 1%-2% improvement for each 100 lbs removed.
6. Using the correct weight lubricants: up to 2% improvement
7. Using low rolling resistance tires: up to 2% improvement
8. Maintaining the correct tire pressure: up to 0.3% improvement for each 1 psi
9. Using cruise control: variable improvements
10. Minimize driving with a cold engine/vehicle: variable improvements
11. Removing unused roof racks and other things carried outside vehicle: variable improvements
12. High-flow air filters: no improvement in mpg but potentially better performance
13. Rolling down windows instead of using A/C: no improvement on the highway, variable improvements at lower speeds
14. Gas mileage improvement gadgets: no improvements and potential fuel system or engine damage (from link to Federal Trade Commission web site)

In addition to the list above, these are specific things that may help gas mileage in the UZJ100 (from forum searches related to gas mileage and maintenance items).

Likely to help:

Oxygen sensor replacement
Catalytic converter replacement
Correct wheel bearing preload
Throttle body cleaning
Mass air flow sensor cleaning
Engine control module reset
Vacuum leak repair
Spark plug replacement

May or may not help:

Spark plug brand/type
Gas brand
Gas formulation (except for high ethanol content gas, which lowers gas mileage)
Gas octane
Installing a tuning chip
Time of day gas fill ups
Differential oil brand
Engine oil brand
Wow... assuming your tires are 1 PSI low, do all those things and you should see an 85.3% improvement in gas mileage!!! :hillbilly: :ban:

But seriously... for the "likely to help" list, I'd like to see what sort of mileage improvement you could expect and calculate how many miles of driving it would take to make it cost-effective... aren't new cats REALLY expensive?
•Drive it.
•Wheel it.
• enjoy it

it's a heavy truck with a V8, no matter what you do. You won't keep up with a Prius. Maybe if you turn it off going down big hills :) .

Then again. My foots made out of lead.... I get rounghly 250 out of a tank. I might just see how many miles I can't get.
Strikes me as ironic how the aftermarket is full of air filters, intakes, exhausts, and tuners that propose to up MPG...

...and at the end of the day...

driving like your granny does saves more gas than all of 'em combined!
2. Driving the speed limit instead of faster: up to 23% improvement

How does "obeying the law" (driving the speed limit) improve your mileage?

So if the speed limit is 35, 45, 55, 65, 75...that doesn't matter? It's whether or not you go OVER the speed limit. Hilarious! :D
For the amount of time and money you're going to spend doing all the "stuff" mentioned, buy an old civic, corolla, etc as a DD. A Land Cruiser is not going to get good mileage no matter what you do unless it sits in the garage! You might save 1-2 mpg's but is it worth the effort? Not trying to be a smart a$$, just realistic. :grinpimp:

Here is a chart of gas mileage at various speeds with a 2004 UZJ100 with 59,000 miles. The data points were checked twice and are with the speed held steady for at least a minute at 10 mph increments on a level highway. I drew a curve between the points. The conditions:

60 degrees
No wind
A/C off
Windows closed
Tire pressure 30F 32R
Roof bars at rear
All vehicle service up to date
Mobil 1 5-30W oil
Michelin LTX AT2 tires
Rear seats removed
No extra load in vehicle
2 adults
MPH determined with both speedometer and a Garmin Nuvi 750 GPS
MPG determined with factory navigation system Trip Info continuous readout
25 mpg? In nuetral?
I don't think you could get 25 mpg going downhill with a tailwind? Maybe if the 100 was on a trailer?
how to get 25 mpg with a 100:

1)Call a friend
2) have him pick you up
3) leave 100 at home
4) go out
5) come back

I couldn't imagine getting 25mpg. Then again 20 mph it should shift into 2nd or 3rd and end up having the RPM's sit near idle. (900-1100 rpms) still unlikley.

Any one with a scangauge, can you give it a shot to get 25mph?
I try to stay left and get as close as I can for some NASCAR style drafting.

I do that too, but apparently the fuzz doesnt like it.

For the amount of time and money you're going to spend doing all the "stuff" mentioned, buy an old civic, corolla, etc as a DD. A Land Cruiser is not going to get good mileage no matter what you do unless it sits in the garage! You might save 1-2 mpg's but is it worth the effort? Not trying to be a smart a$$, just realistic. :grinpimp:

I got 35mpg in utah & wyoming yesterday going considerably faster then the limit, (well that was in an aerodynamic 480hp car not a 6500lb 100) and then 27mpg east of wyoming. Same thing with the LX a few weeks ago, I get better gas mileage at high altitude with elevation changes then I do down at sea level.

Its something I think about when I'm traveling long distances (IE: Driving from Nevada to New York twice in a month). Around home theres too much traffic and I'm too WOT to care.
I always laugh when it comes to mpg in a 100. Yep, I'd like to get a few more miles per gallon, but honestly, this isn't the rig to accomplish that. :D

That being said, with armor and bigger tires, it's gonna drop.

I have never checked my mpg and I don't really care. I drive the 100 and 60 combined maybe... less than 5K a year.

My daily driver is a Masi Fixed Gear Especial or the GT Avalanche, or the New York City Subway.

I'm fortunate to have choices and feel bad for you guys that have to drive your hundies every day. :cheers:
I feel bad for your hundred for having to sit on the street all the time. I enjoy driving mine more then any other vehicle, people GTFO of my way. Plus no SUVs nearly hitting me causing me to throw rocks at them........
Better mileage than an 80... or my 94 Runner 3.0. Pulled a drift boat trailer and still got 310 on the tank. Did not go over 75 mph. Maybe it is the 285 Big O tires!
Last month's trip to the coast gave 400 miles between fill-ups going around the Olympic Peninsula. Full car, 4 persons, dog, decent weather, little wind, and temp in the low 60ies. But also slow/careful on the accelerator. Not bad considering I normally only get about 330 miles around town (very hilly) per fill-up
In town I look with envy at my Prius owning friends, but out on the open road, car full of stuff, nothing beats the 100 - and it still gets better mileage than comparable (if they even exist) vehicles.
Cost of traveling in style!
I'm even more surprised to see it drop to 10 at 85 MPH. I usually get about 13-14 MPG at that speed and can get 15 running between 75 and 80 all day long. As for the low speeds, I cannot imagine drag being a problem until 35MPG or so and I'd expect to see a peak in MPG near there.

I have so say that I once got 19 MPG between Victorville and St George though. A wicked tailwind with 60 MPH gusts was greatly appreciated!

Users who are viewing this thread

Top Bottom