GX550 Real World MPG

I don't drive this think like I stole it....I don't baby it or try to hyper-milage either. I mainly drive in normal or comfort mode and generally avoid putting my foot into it unless I have to. My bigger tires (35") haven't made much of a difference (penalty). My best mileage has been all highway travel from Phoenix to San Diego & back on my bigger 35" tires. On the way back from San Diego I kept the cruise control below 80 and it shows (15.92 mpg). On the way there I was at 90 for a good bit of the drive (13.97 to 14.10 mpg). I don't know how in the heck some of y'all are seeing 20 mpg.
19.5 coming home 200 miles cc at 75 2/3 of the way and 80 the rest. Put it in economy mode
 
Reporting back after a few more miles. My average is around 14 mpg (city/hwy) with 21 gallon fuel tank. My larger (and faster) full-size Range Rover gets mid 20s with a 24 gallon fuel tank. Fuel economy seems too low in the GX.

The LX600 has 60 more horsepower, weighs more, and gets better fuel efficiency than the GX. Same 10 speed transmission. I'd like to know why. Can't all be aerodynamics.

Related thread on GX vs LX fuel economy: Why does the GX550 get worse MPG than the LX600?
 
I didn’t reset my meter for the first 3500 miles and average 17.4 miles per gallon

On a 40 mile trip to work mostly highway I turn off the car and it says I got 20.4 miles per gallon not bad.

And other people have shown that the cars mpg seems to be a little bit low from what the measured with gasoline and miles gives you.
 
A couple tanks of fuel ago I decided to make sure octane rating didn't make a difference. I can only get 91 octane at the gas stations around here but there is a gas station that happens to also sell 95 and 100 octane fuel. So I ran the GX down near empty (or as close as I dare with the incredibly inaccurate fuel gauge) and pumped in 9.25 gallons of 91 octane in and then 9.25 gallons of 95 octane. That's 18.5 gallons of 93 octane average on top of the 2.6 gallons of 91 octane that remained in the tank, so my true octane rating was 92-point-something. My fuel average was lower than average at 12.21 gallons based on miles driven divided by gallons burned. And the tank was much more expensive than average thanks to the $6/gallon 95-octane gas.

I'm finding that the main contributing factor is the type of driving, and economy mode also does make a difference. On my current tank (the tank after the race fuel experiment) I filled up at the local Costco and for the first three days my only driving was taking my boys to school, picking them up, going to karate lessons, baseball practice, etc. All local city driving, lots of stop lights and stop signs, inching through waiting lines, etc. and no highway at all. I was at 9.X mpg. So yesterday I put it in economy mode doing the same city driving and the fuel indicator inched up over 10 mpg. Then I did about a 20-mile highway run last night and I'm currently in the 11s. I also noticed that economy mode sucks. Feels like I'm driving a Yugo, or what I imagine a Yugo would drive like.
 
A couple tanks of fuel ago I decided to make sure octane rating didn't make a difference. I can only get 91 octane at the gas stations around here but there is a gas station that happens to also sell 95 and 100 octane fuel. So I ran the GX down near empty (or as close as I dare with the incredibly inaccurate fuel gauge) and pumped in 9.25 gallons of 91 octane in and then 9.25 gallons of 95 octane. That's 18.5 gallons of 93 octane average on top of the 2.6 gallons of 91 octane that remained in the tank, so my true octane rating was 92-point-something. My fuel average was lower than average at 12.21 gallons based on miles driven divided by gallons burned. And the tank was much more expensive than average thanks to the $6/gallon 95-octane gas.

I'm finding that the main contributing factor is the type of driving, and economy mode also does make a difference. On my current tank (the tank after the race fuel experiment) I filled up at the local Costco and for the first three days my only driving was taking my boys to school, picking them up, going to karate lessons, baseball practice, etc. All local city driving, lots of stop lights and stop signs, inching through waiting lines, etc. and no highway at all. I was at 9.X mpg. So yesterday I put it in economy mode doing the same city driving and the fuel indicator inched up over 10 mpg. Then I did about a 20-mile highway run last night and I'm currently in the 11s. I also noticed that economy mode sucks. Feels like I'm driving a Yugo, or what I imagine a Yugo would drive like.
From what I am seeing your numbers are way lower than what I am getting. Kind of tough to know for sure how different your driving is. I am still bone stock. I have been using 93 i believe. Driving around town, not stop and go but not highway i was 18-19 ish in normal mode.
 
From what I am seeing your numbers are way lower than what I am getting. Kind of tough to know for sure how different your driving is. I am still bone stock. I have been using 93 i believe. Driving around town, not stop and go but not highway i was 18-19 ish in normal mode.
What trim do you have?

For sure, the tires on the stock Overtrail will make a difference vs the road tires on a Luxury or Premium trim model. And I am beyond the stock 33" Overtrail Toyo AT3 tires with my 35" Toyo AT3s.

I fully expected to pay about a 1 mpg penalty with my oversize tires. I was at an average of 14.20 before my lift & new tires. I am now at an average of 13.79 mpg. Really an insignificant 3% difference.

I'm heading to northern AZ camping this weekend with a good 100 miles highway there and then again 100 miles back. Mileage on the way up will suffer with over 5,000 feet of climbing but I'll average the highway trip up & back. I'll see if I can tolerate economy mode the whole way there & back again.
 
What trim do you have?

For sure, the tires on the stock Overtrail will make a difference vs the road tires on a Luxury or Premium trim model. And I am beyond the stock 33" Overtrail Toyo AT3 tires with my 35" Toyo AT3s.

I fully expected to pay about a 1 mpg penalty with my oversize tires. I was at an average of 14.20 before my lift & new tires. I am now at an average of 13.79 mpg. Really an insignificant 3% difference.

I'm heading to northern AZ camping this weekend with a good 100 miles highway there and then again 100 miles back. Mileage on the way up will suffer with over 5,000 feet of climbing but I'll average the highway trip up & back. I'll see if I can tolerate economy mode the whole way there & back again.
I have an overtrail plus with the stock tires until Friday, but then I am just going up to 275 70 18's little wider, little taller, but the e rating sidewalls. Roads up north in Maine have a lot of shale which eats sidewalls if you don't have 10 ply tires. But not lifting or anything, so don't think the mileage should change much.
 
I'll be interested to hear if your new tires make any noticeable changes to you average mileage. Being wider and heavier, they should decrease mileage but it may be an insignificant amount. Also being taller, your speedometer and odometer will be off a bit, so that will come into play - you will be traveling farther and faster than your speedometer and odometer are recording.
 
Reporting back after a few more miles. My average is around 14 mpg (city/hwy) with 21 gallon fuel tank. My larger (and faster) full-size Range Rover gets mid 20s with a 24 gallon fuel tank. Fuel economy seems too low in the GX.

The LX600 has 60 more horsepower, weighs more, and gets better fuel efficiency than the GX. Same 10 speed transmission. I'd like to know why. Can't all be aerodynamics.

Related thread on GX vs LX fuel economy: Why does the GX550 get worse MPG than the LX600?
Windshield is more upright, full time 4wd, smaller turbos (lower cylinder compression ratio), less ground effect aerodynamics
 
I have an overtrail plus with the stock tires until Friday, but then I am just going up to 275 70 18's little wider, little taller, but the e rating sidewalls. Roads up north in Maine have a lot of shale which eats sidewalls if you don't have 10 ply tires. But not lifting or anything, so don't think the mileage should change much.
Which tires are you changing to? I'm going to run stock tires for now, but I've really been looking at the Mickey Thompson Baja Boss A/T in 275/70/18. They are heavy but they look pretty amazing.
 
I have a new set of the Baja Boss AT's on our 80 series. Super meaty up close in person. Roll nice but do have more of a light note and some times take a bit to "warm up" before smoothing out. I like the full range spec of the tire.
 

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I have a new set of the Baja Boss AT's on our 80 series. Super meaty up close in person. Roll nice but do have more of a light note and some times take a bit to "warm up" before smoothing out. I like the full range spec of the tire.

Those look pretty dang awesome on there. Thanks for the insights too.
 

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