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Discussion Starter · #1 ·
I just returned from a 3,000 mile round trip vacation from Hayward, CA (my home) to Yellowstone National Park and the Little Bighorn Battlefield. I kept some records of my FJ’s fuel consumption that I’d like to share with you.

My average MPG for the entire trip was 20.68 MPG. I drove in a wide range of driving conditions, as you can imagine for a trip of this length. Before I departed I changed my oil with Mobil 1 synthetic, as I heard that synthetic oil can increase gas mileage.

I used both regular and premium fuel, but it didn’t seem to make a difference to my fuel economy. For instance, on the way to Yellowstone I used premium fuel on US 80 between Reno and Elko, Nevada. My MPG was 19.23. On the way back I used regular fuel through this same stretch of road, and my MPG was 18.93. It should be noted, however, that on the way back I was driving into a 40+ mph headwind. While driving through Nevada, both ways, my cruise control was set at 83 mph – not a good speed for saving fuel but Nevada is made for driving fast.

My best gas mileage came on the days I spent driving in and around Yellowstone park. On those days my speed was kept under 55 mph, but I stopped on a regular basis for bison traffic jams, wolf sightings, elk herds, etc. My average MPG for this kind of driving was about 22.6. My best single day for gas mileage came when driving south through Yellowstone, Grand Teton National Park, to Alpine, Wyoming. On that day I got 23.67 MPG (210 miles, 8.88 gallons of regular).

I kept lots of records, but I won’t bore you with much more. But my conclusions are that: 1) it doesn’t seem to matter if I use regular or premium, gas mileage for my FJ is about the same for each; 2) the best fuel economy comes when speed if kept between 45 - 55 mph (no surprise here); and 3) driving at 80 mph will limit your fuel economy to about 19.5 MPG.

It was a wonderful trip and my FJ was great. All in all, I drove 3,195 miles in 10 days. My only scare came when my “maintenance required” dash light went on while driving through the middle of nowhere in Nevada. It took me a little while before I remembered that this light is just a reminder to change your oil at 5,000 miles (I changed mine at 2,000 before the trip but forgot to reset the odometer). Needless to say I was greatly relieved!

I hope some of you have found this useful/interesting. Take care!
 

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Thank you Roy - that is the kind of scientific info that is a pain to collect yet the most useful.

How stock is your setup? 23.67 mpg is exactly 10 mpg more than I can possibly get going 60 mph on the freeway. Whatever you're doing, you are a new kind of hero on this forum...
 

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Thanks for sharing the info, but you got some pretty good MPGs compared to what I get. :bigthumb:The best I could get was about 17mpg going 75mph on a 6MT.:simmadown:
 

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Damn Roy! You must be an expert driver. I haven't driven enough road trips to really get a handle on what my averages might be at sustained highway speeds. My mixed highway city mileage is pathetic most of the time. Almost 17 mpg is about the best I have been able to do. My lead foot gets in the way alot. I would be very happy if I could consistently do as well as you are doing. I'm trying to train myself, but I keep sliding back into my old driving habits. Developing a driving style which conserves fuel is more difficult than I thought it would be.
 

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The only way to get max MPG with the FJ:
No mods that add weight and/or impact aerodynamics.
Stay under 2000 RPM.
Smooooooth application of brakes and throttle.
Fuel prices won't be going down...oh, they'll throw us a bone and it may come down a little but unless it's a $1 less than current it won't help much.
 

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I kept lots of records, but I won’t bore you with much more. But my conclusions are that: 1) it doesn’t seem to matter if I use regular or premium, gas mileage for my FJ is about the same for each; 2) the best fuel economy comes when speed if kept between 45 - 55 mph (no surprise here); and 3) driving at 80 mph will limit your fuel economy to about 19.5 !

I hope some of you have found this useful/interesting. Take care!
I have found these statements to be true. :bigthumb:
 

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Discussion Starter · #9 ·
Thank you Roy - that is the kind of scientific info that is a pain to collect yet the most useful.

How stock is your setup? 23.67 mpg is exactly 10 mpg more than I can possibly get going 60 mph on the freeway. Whatever you're doing, you are a new kind of hero on this forum...
My FJ is completely stock on the outside, except for a bug shield I added to the hood. I don't have a roof rack, which may offer better areodynamics.

I failed to mention in my post that I have an automatic transmission.

I was suprised by the fuel economy I got, but I double checked all of my math. I calculated my MPG simply by dividing the miles I drove by the gallons I used. Whenever I filled up I zeroed out my trip odometer. I also tried to be consistent with the way I topped off my tank.

Could Mobil 1 Synthetic oil improve fuel economy to this degree? I also used cruise control a lot, which probably helped.

My driving up to the point of my trip has been around town and some on freeways. I think my MPG is around 17 MPG for that kind of driving, but I think I will start keeping better records of that. I've been planning to add a 3" lift kit to my FJ, but now I'm having second thoughts.

Take care!
 

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Roy, your mpg is consitent to what I have been seeing. I've even hit 25 mpg 6 times in the last 18 months. Stock, 5AT, no roof rack, stock tires, high altitude driving, no city driving, no commuting.

DEWFPO
 

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I wish!
 

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Roy how many miles are on your truck? I only have 1500 miles on mine and best i can get is 17? wonder if it is still tight yet?
 

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I have found similar results to yours Roy. In the warm weather I get 22 mpg in both the city (50 km/h - 60 km/h) or highway (100 km/h - 120 km/h) whether I use premium or regular. That 22 mpg is based on the Imperial gallon, not the U.S. gallon. Now, in the winter time...well, that's a whole different story.
 

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Discussion Starter · #14 ·
Roy how many miles are on your truck? I only have 1500 miles on mine and best i can get is 17? wonder if it is still tight yet?
I had 2114 miles on my FJ when I left for my trip. Had 5314 when I returned.

Do you think altitude has something to do with good fuel economy? I suppose there would be less drag at higher altitudes. On the day I got my best mileage all of my driving was above 6500 feet, and I crossed the continental divide twice in Yellowstone at about 8200.
 

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I had 2114 miles on my FJ when I left for my trip. Had 5314 when I returned.

Do you think altitude has something to do with good fuel economy? I suppose there would be less drag at higher altitudes. On the day I got my best mileage all of my driving was above 6500 feet, and I crossed the continental divide twice in Yellowstone at about 8200.
I know it does. I live at 7,200' and most all my driving is above 5,700'. It's not so much the drag but the air is thinner and the ECM compensates by using less fuel to maintain the proper balance. So I get great mileage but I'm also making much less HP and TQ. Depending on who you quote, you loose anywhere from 3.0 - 3.7% for every 1,000' you go up in altitude.

A supercharger would bring allot of that loss back, at the cost of fuel economy and much lighter wallet. It's a tradeoff.

DEWFPO
 

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For the guys here getting low mpg on your newer low-mileage FJ, there is a break-in period setting on the ECU that keeps you in Open Loop until X number of miles on the odometer. You will be running rich until then.

What the number of miles is, I can't remember. But it is on the forum somewhere.
 

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yep i think your results are consistent with an unmodded or lightly modded FJ.....put on a set of 33" tires and it will lose 2-3 mpg off the bat.

Good job.... I got 17-18mpg on trip frm Charleston to Wash DC in April......at 69mph and 1950rpms.
 

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I would be curious to know what kind of mileage one would get with a supercharger/CAI/CBE installed.

Anyone?
 

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I consistently get 300 miles per tankful before the low fuel light comes on. That is about 19.5 MPG average per tankful. But I was not using cruise, and the average speed was 70-75 MPH on the freeway with run-n-gun on freeway onramps. This is with a 2007 5AT 4X2 with 4X4 factory springs and shocks (lifted about 2" in front from original), OEM sliders, roof rack and bling plate.

Since my last fill up, I have not gone above 65 MPH, set the cruise control on the freeway at 62 MPH and settled in behind tractor-trailers, and smooth acceleration at lights/getting on the freeway. I've gone 170 miles, and the fuel gauge is not even down to the 1/2 way mark yet. More to come on this. Oh, and I'm still running the Toyota synthetic blend oil.
 
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