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Discussion Starter · #1 ·
Hey all-
Have a 2018 2WD with the V6. Put 31.5 in tires on it. I’m getting 11.5 MPG. I know the tires have an impact, both real and perceived as it throws off the speedo.
But I also have a 6.2 liter Raptor with 33s and I get 11 in that truck.
I had a dealer test the Colorado - oxygen sensor and all other things are good.
But something has to be wrong here if I’m only getting 11.5 mpg.
Any ideas?
 

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Hey all-
Have a 2018 2WD with the V6. Put 31.5 in tires on it. I’m getting 11.5 MPG. I know the tires have an impact, both real and perceived as it throws off the speedo.
But I also have a 6.2 liter Raptor with 33s and I get 11 in that truck.
I had a dealer test the Colorado - oxygen sensor and all other things are good.
But something has to be wrong here if I’m only getting 11.5 mpg.
Any ideas?
That is a feasible number to be displayed. There are a few factors that can decrease your actual mpg's.
First the tire design. If you chose knobby mud terrain tires or even Duratracs then those by default will rob you of your mileage.
Second is the load range. If you went away from factory load range of SL or C then you have added a heavier tire size for size and you increased the size at the same time.
Third is pressure. If you are running a lower pressure in relation to the max pressure of the tires then you will lose more. Example; 35 psi on a factory tire is ok. But 35 psi on a load range E tire with a max of 80 psi is completely different.
Fourth would be power. The gas motor trucks make their power high in the room band. Putting your foot down to get there faster can actually increase your mileage. But you can't overcome the gearing behind the V6 for larger tires. You would need to regear the differential to overcome that.
Fifth is the speedo issue. There is more than just a perceived difference in the speed and mileage. All the calculations the ecm does are based on specific speeds and results. Those are now off.

I have a ZR2. I have the v6. I too don't have great mileage but that said I have maximized what I could from this model.

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I have a ZR2 with V6 also - 2021. Previously had a 2017 ZR2 - the 2021 seems to get a bit better gas mileage. You might want to put the driver information center display on instant gas mileage for a bit to watch / see how much influence your driving style has on the gas mileage. It's substantial. As a point of reference - I routinely get around 15-17 mpg with in town driving. 11 mpg is pretty poor although it might be low teens considering tire / speedo correction issues.
 

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is that all city driving, highwaay or combo?

is that with mileage correction with the larger tires? what odometer says will be less then actual with larger diameter tires

I can drive my ZR2 to get 11 or 20 same with my friends Raptor
 

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Discussion Starter · #6 ·
That is a feasible number to be displayed. There are a few factors that can decrease your actual mpg's.
First the tire design. If you chose knobby mud terrain tires or even Duratracs then those by default will rob you of your mileage.
Second is the load range. If you went away from factory load range of SL or C then you have added a heavier tire size for size and you increased the size at the same time.
Third is pressure. If you are running a lower pressure in relation to the max pressure of the tires then you will lose more. Example; 35 psi on a factory tire is ok. But 35 psi on a load range E tire with a max of 80 psi is completely different.
Fourth would be power. The gas motor trucks make their power high in the room band. Putting your foot down to get there faster can actually increase your mileage. But you can't overcome the gearing behind the V6 for larger tires. You would need to regear the differential to overcome that.
Fifth is the speedo issue. There is more than just a perceived difference in the speed and mileage. All the calculations the ecm does are based on specific speeds and results. Those are now off.

I have a ZR2. I have the v6. I too don't have great mileage but that said I have maximized what I could from this model.

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Wow - thank you for all of this. I’ve been perplexed because the raptor is barely off from what it was before the tire change and the Colorado went from 14-15 down to 11. So it’s been pretty frustrating to try and figure it out.
I’ve learned how to drive the raptor and like you said, you can’t baby it. I find when I drive it the right way, it’s pretty good
is that all city driving, highwaay or combo?

is that with mileage correction with the larger tires? what odometer says will be less then actual with larger diameter tires

I can drive my ZR2 to get 11 or 20 same with my friends Raptor
This is city and all of the calculators I’ve tried to figure the implicit form the larger tires on the speedo alone are 1 to 1.5 mpg correction.
It seems someotng is wrong to me.
 

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Wow - thank you for all of this. I’ve been perplexed because the raptor is barely off from what it was before the tire change and the Colorado went from 14-15 down to 11. So it’s been pretty frustrating to try and figure it out.
I’ve learned how to drive the raptor and like you said, you can’t baby it. I find when I drive it the right way, it’s pretty good

This is city and all of the calculators I’ve tried to figure the implicit form the larger tires on the speedo alone are 1 to 1.5 mpg correction.
It seems someotng is wrong to me.
Look up the exact rolling circumference of each tire and get the percentage difference. Then apply that to your speed and it can also apply to the not in the dic. However that will be a smidge off because of the algorithm gm uses. You are likely near 2% difference in rolling circumference. So say your speedo reads 60mph you are really doing 61.2mph. The lower the speed the less difference there is.

Glad I could help.

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put it the oem and your aftermarket tires in this calculator and it will give you the difference at any speed

what tires did you go to?

 
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hey,

I have a few ideas.

1) is it winter gas in your area? - winter gas blend has a chemistry that improves cold starting, but causes a reduction in mileage
2) do you have the air dam removed?
3) what tires do you have on it? they could be under inflated. for example I'm running stock size (255/65/17 - KO2s but need to run them 5 psi more than the door sticker to get the same load rating. (here's some math. find out your vehicles GVWR, then divide that by 4 for the load at each corner (example my truck is 6200 lbs/4 = 1550 lbs, then find out the load rating for the given tire you are running , example if the tire is rated for 2600 lbs @ 65 psi, then its load rating is 40 lbs per psi. So 1550/40 = 38.75 psi. My oem tire math works out to be ~33 psi, but the door sticker says to run 35 psi.
also, like others have said, you will have to figure out how much your speedo is off and do the math for that as well.
4) pending all that - maybe you have bad gas - try a different vendor?
5) check your air filter and oil make sure they are good.
6) pending all that again, perhaps you have an issue with your engine - I would check the compression of each cylinder.

For the record my truck is diesel and is averaging 26 mpg.
 

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we are on winter gas here in the Central part of the country and I can tell it on both vehicles..
Same here. Took the hit on fuel economy a bit so I bumped my tire pressure up 5psi to compensate a bit.

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Scan it and check short and long term fuel trims.
 

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That is a feasible number to be displayed. There are a few factors that can decrease your actual mpg's.
First the tire design. If you chose knobby mud terrain tires or even Duratracs then those by default will rob you of your mileage.
Second is the load range. If you went away from factory load range of SL or C then you have added a heavier tire size for size and you increased the size at the same time.
Third is pressure. If you are running a lower pressure in relation to the max pressure of the tires then you will lose more. Example; 35 psi on a factory tire is ok. But 35 psi on a load range E tire with a max of 80 psi is completely different.
Fourth would be power. The gas motor trucks make their power high in the room band. Putting your foot down to get there faster can actually increase your mileage. But you can't overcome the gearing behind the V6 for larger tires. You would need to regear the differential to overcome that.
Fifth is the speedo issue. There is more than just a perceived difference in the speed and mileage. All the calculations the ecm does are based on specific speeds and results. Those are now off.

I have a ZR2. I have the v6. I too don't have great mileage but that said I have maximized what I could from this model.

Sent from my Pixel 6 Pro using Tapatalk
These five, plus one other significant factor is that if you let the truck sit and idle a lot or use remote start often, then that fuel usage counts against your overall fuel mileage. Years ago the calculation was different and only considered fuel used in Drive gears, but now thanks to the stupid EPA, they also have to count what is used in Park.
 

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These five, plus one other significant factor is that if you let the truck sit and idle a lot or use remote start often, then that fuel usage counts against your overall fuel mileage. Years ago the calculation was different and only considered fuel used in Drive gears, but now thanks to the stupid EPA, they also have to count what is used in Park.
Thank you! Totally forgot to add that. Remote start has been a fairly aggressive fueling compared to start, wait a minute, then drive the rest of the warmup. So of course sitting in drive thru lines in colder months will effect it more as well

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Thank you! Totally forgot to add that. Remote start has been a fairly aggressive fueling compared to start, wait a minute, then drive the rest of the warmup. So of course sitting in drive thru lines in colder months will effect it more as well

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Fuel usage always goes up in winter because 1. people tend to leave the engine running more for heat, and 2. winter weather causes more traffic delays/slow downs.

So if we're traveling the same amount but using more fuel then our MPG is obviously reduced in the winter time. I think some people tend to attribute these drops in MPG to the fuel blend, but it's really not as much of a drop in fuel efficiency as it is a change in usage and driving conditions.
 

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Fuel usage always goes up in winter because 1. people tend to leave the engine running more for heat, and 2. winter weather causes more traffic delays/slow downs.

So if we're traveling the same amount but using more fuel then our MPG is obviously reduced in the winter time. I think some people tend to attribute these drops in MPG to the fuel blend, but it's really not as much of a drop in fuel efficiency as it is a change in usage and driving conditions.
I disagree
we drive our vehicles the same route 425 miles each way on Interstate 70 from Stl to Salina Kansas during the summer and winter and the traffic is pretty much the same and we drop at least 2 mpg in either of our vehicles during the winter.

Also we park our vehicles in the garage and never "warm" them up and there is not any congestion where we live...

The head guy over the North American Fluids Division of a major oil company told me the winter blend in STL is the worse in the country for gas mileage.
 

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I disagree
we drive our vehicles the same route 425 miles each way on Interstate 70 from Stl to Salina Kansas during the summer and winter and the traffic is pretty much the same and we drop at least 2 mpg in either of our vehicles during the winter.

Also we park our vehicles in the garage and never "warm" them up and there is not any congestion where we live...

The head guy over the North American Fluids Division of a major oil company told me the winter blend in STL is the worse in the country for gas mileage.
I disagree because we can pretend that we don't change our vehicle use when it's cold, or that winter traffic and driving conditions are identical to the summer...but that would still be ignoring the ice, snow, heavy winds and increased night driving because there is less day time during the winter.

Driving in ice or snow reduces fuel mileage.

Driving in wind reduces fuel mileage.

Driving at night obviously uses the alternator more which will reduce fuel mileage.

And we can pretend that we don't run vehicles more for heat during winter, but we probably still use heated seats, which also use electricity and that doesn't come out of thin air...it comes from our alternator, which in turn reduces fuel mileage.
 

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Don't forget air density in relation to temperatures. Cold air is more dense, in order to maintain the correct AFR more fuel has to be used. The bonus is that you can see a nice performance boost in cooler or cold weather.

There are actually a lot of other factors at play when it comes to winter fuel economy that many people don't realize or think about. It's easy to blame winter blend gas, but the energy content difference between winter and summer gas is only like 1.7%. That's not a huge impact. The weather itself and the items listed in the URL below have a greater impact on fuel economy than summer vs winter blend gas.


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I disagree because we can pretend that we don't change our vehicle use when it's cold, or that winter traffic and driving conditions are identical to the summer...but that would still be ignoring the ice, snow, heavy winds and increased night driving because there is less day time during the winter.

Driving in ice or snow reduces fuel mileage.

Driving in wind reduces fuel mileage.

Driving at night obviously uses the alternator more which will reduce fuel mileage.

And we can pretend that we don't run vehicles more for heat during winter, but we probably still use heated seats, which also use electricity and that doesn't come out of thin air...it comes from our alternator, which in turn reduces fuel mileage.
Too many variables for too many different people.
As an example or three....
not all have snow and/or ice, which way is the wind blowing, could be driving more at night, maybe not. A/C use is a lot less in the winter, and when it's used for defog for example the system is more efficient in colder air. I don't have heated seats, heat from the core is free.
Around here "they" (whoever "they" are) say the winter gas sucks. This could be a big factor I don't know. My mileage with this E10 sucks all the time, it doesn't matter what the weather is. lol
 
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I disagree because we can pretend that we don't change our vehicle use when it's cold, or that winter traffic and driving conditions are identical to the summer...but that would still be ignoring the ice, snow, heavy winds and increased night driving because there is less day time during the winter.

Driving in ice or snow reduces fuel mileage.

Driving in wind reduces fuel mileage.

Driving at night obviously uses the alternator more which will reduce fuel mileage.

And we can pretend that we don't run vehicles more for heat during winter, but we probably still use heated seats, which also use electricity and that doesn't come out of thin air...it comes from our alternator, which in turn reduces fuel mileage.
on these trips we drive during the day, the wind in Missouri and Kansas blows prettty much the same year round, we also do not make these trips when there is ice or snow on the interstate. We do not use remote start on either vehicle on these trips, nor sit at an idle. we do not use the heated seats on these trips, but we do listen to tunes, and depending on how loud we have the volume up, will depend on how hard the alternator has to run which can drastilcaly reduce gas mileage

so I guess if we turn the volume down on these trips during the winter we will get the same gas mileage that we do when using the summer blend of gas, who knew...
 
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