2008 V8 Gas Mileage
- Thread starter AKABlig
- Start date
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For the sake of statistical ease, lets pop out those outliers. Bad math or weird circumstances that cannot be a. repeated or b. nailed down can cause them.
Once we throw out the outliers, you have an obvious trend. Your slow, gradual down curve could be caused be a million little things that occur over time, that alone may not matter, but in combination add up to the percentage drop you are seeing.
Older tires, that have off inflation? Dirty air filter? Plugs?
I am obviously spitballing. You do not appear to have an instant, dramatic change (outliers disregarded)... and therefore it is really hard to speculate.
Edit: On second thought. Your mid graph highs are clearly outliers, but I am now not so sure about your end graph low scores.. You continue to see your average highs, but your lows are popping down.
If you get me the actual data. An excel or comma delimited file; I can run some numbers and see what is up. Also, can you get any more data points after your last set?
What I would like to see is some more data Further Along....... to see if those are outliers or in fact a new trend.
Once we throw out the outliers, you have an obvious trend. Your slow, gradual down curve could be caused be a million little things that occur over time, that alone may not matter, but in combination add up to the percentage drop you are seeing.
Older tires, that have off inflation? Dirty air filter? Plugs?
I am obviously spitballing. You do not appear to have an instant, dramatic change (outliers disregarded)... and therefore it is really hard to speculate.
Edit: On second thought. Your mid graph highs are clearly outliers, but I am now not so sure about your end graph low scores.. You continue to see your average highs, but your lows are popping down.
If you get me the actual data. An excel or comma delimited file; I can run some numbers and see what is up. Also, can you get any more data points after your last set?
What I would like to see is some more data Further Along....... to see if those are outliers or in fact a new trend.
Last edited:
onemoreokie
New member
Ethanol perhaps
^this^ I noticed when traveling through Ga. where NON-ethanol gas is hard to find that i get up to about 30-40 miles LESS per tank and the only difference is the ethanol gas premium or regular.
You can attach the file up here. Zip it up or rename it .txt if it is an excel format. Just let me know what it actually is, so I can know what to rename it.
I can throw it in my stats program and take a look. I can already tell you, that those end point lows are skewing your average down. That we need to figure out. If you pull those several points out, I can already see just from spit balling, that you are well within accepted average. You have to assume that there are literally a thousand variables working at any time to factor in your MPG, so an up or down is expected. Which you see.
I can throw it in my stats program and take a look. I can already tell you, that those end point lows are skewing your average down. That we need to figure out. If you pull those several points out, I can already see just from spit balling, that you are well within accepted average. You have to assume that there are literally a thousand variables working at any time to factor in your MPG, so an up or down is expected. Which you see.
12guns
New member
Hard to say...there are TONS of things that will affect MPG. I found a rather large increase when I added just a few PSI per tire. Any chance yours have dropped just one or two PSI over the 25k miles? Wearing tires may affect MPG if not rotated regularly, but you may be on top of that already. What about a stuck piston in one or more calipers? I wonder if there is an overall "lower" quality of gas over the past couple years? I know gas quality can vary greatly from time to time and station to station. Dirty air filter? Dirty MAF? Worn spark plugs? Just a few thoughts. Hope you nail it down! Let us know if you do.
chayos00
New member
Before getting my lift on my truck I too have noticed the same gradual drop in my average for MPG. When first getting the truck I was getting 21-22mpg, then down to high 19's to low 20's. New plugs and air filters didn't do any good. Plus I always ran my tire psi from 35-37psi. This was up to around 45K on the truck.
Now with my lift and tires I'm doing 18's.
Now with my lift and tires I'm doing 18's.
anotherrunner83
New member
I have often wondered if the gradual wearing of a tire, causing a change in the tire diameter plays with these numbers. I have gotten 19 mpg on a flat haul from Chattanooga to Augusta several times. If I head north and go over the mountains to Cincinnati, I usually get around 17 or so. My last trip was 15, but driving style and cooler temperatures played into that. I've also gone to larger tires, which has the largest impact on that number, but surprisingly, in day to day driving, it has had little impact. There are just so many variables that play into gas mileage...
anotherrunner83
New member
After looking at your numbers again, you may have an O2 sensor beginning to fail on you. Most of your numbers were relatively close to what I average in my 08 V8 until recently.
