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Discussion Starter · #1 ·
I'm not quite a hyper-miler but my driving style is certainly not aggressive. I frequently buy non-ethanol premium and I am noticing that I get considerably better fuel economy with the non-ethanol than I do with ethanol-blended fuel. While no two trips are exactly the same, I am becoming convinced that my fuel economy is at least 10% better with the non-ethanol premium.

Professional websites are saying that ethanol-blended fuel reduces fuel economy by about 3%. I'm finding the difference to be much greater. Granted the non-ethanol premium costs about 10% more, but if I'm using 10% less fuel it's a wash.

Three Questions:
1. Can anyone else verify my experience?
2. Is the difference because I'm using premium, or is it because of the ethanol?
3. Since ethanol is alcohol, does using ethanol mean I can skip the drygas in the winter?
 

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Three Questions:
1. Can anyone else verify my experience?
2. Is the difference because I'm using premium, or is it because of the ethanol?
3. Since ethanol is alcohol, does using ethanol mean I can skip the drygas in the winter?
1- yep. I consistently see a 2.5-3MPG gain running ethanol free fuel.
2- it's the lack of ethanol. Running premium is a waste unless your engine is pulling timing due to knock (unlikely).
3- I can't comment on; no real winters here in the south . But ethanol does break down faster than regular fuel, so fuel stabilizer is needed for long-term storage. I'd imagine It's similar to drygas.
 
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Discussion Starter · #3 ·
2- it's the lack of ethanol. Running premium is a waste unless your engine is pulling timing due to knock (unlikely).
It's been years -- ah, decades -- since I did a regular v. premium experiment and I agree. In the 20+ cars I've owned, only a few needed premium.

Premium seemed to make a difference in power in my first car (1960 Ford). It was such a modest power-plant (144CID) that it needed all the help it could get. lol Still, it was my first car and I loved it. May it rust in peace.

I had two Plymouth Volares back when unleaded gas was a new thing. Both had a knock if I used regular gas and in those days it was tough finding premium unleaded. Most stations offered two grades of leaded, but only unleaded regular. My '78 Volare needed a valve job at 80,000 miles. The mechanic even asked me what I was using for gas.

I had a 1986 Buick Electra that had a knock with anything less than 93. It was truly a luxury car, but it was pretty rough on gas. 20MPG was a rare number. I ran premium for fear of burning the valves.

Every other car ran fine on regular.
 

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I never notice a difference, but I don't experiment much (on purpose) or watch it closely either.

On Friday I filled up with 91 octane non-ethanol premium and every time I do that it is for the exact same reason: I am filling a 5 gallon gas can for my boat/lawn mower/etc and since I already have the pump running when my can is full I turn around and top off my tank with the same stuff.

I probably had a third of a tank when I did that on Friday. Probably about once a month I land in that situation where I end up putting the non-ethanol premium in after filling up a can for the mower or boat or snowmobile etc.

My car seems to run the same and get the same mileage no matter what I put in it.

That being said, it takes a very, very long time with hundreds, if not thousands of miles of careful A-B-A testing before anyone can make any (believable) claims about the difference between premium and regular here in my part of the country. There are far too many other variables at play from one tank to the next. Our weather is super inconsistent, winds are changing all the time, huge temperature swings. A person needs to be driving ideally the same road trip over and over and over again and try to earmark the wind/weather from trip to trip to be sure of anything, because weather-related factors alone will bounce you up or down 3 MPG easily and most people unconsciously conflate weather-related factors with a one-off experimental tankful of premium and then claim a result based just on the fuel.

People also consciously bias tank performance if they spend the extra ten bucks for premium they tend to drive on that tank more carefully and consciously than they do with regular, and then their inconsistent driving behavior from the tank of premium fuel further...dilutes... their results. This is less a factor with people trying to get the best MPG all the time on every trip, but tends to affect everyone. Ideally someone else would fill your car and not let you know whether you are running premium or regular from tank to tank, track results over at least 10 tankfuls while trying to drive the same strip in the same manner and hopefully all in the same weather.... doesn't typically happen that way in reality.

In other words, without lab conditions you can't hardly prove anything from a stray tank of premium you throw in here or there on a whim. Any marginal gains that could be lurking in premium fuel are small enough to be washed out by the rest of the variables that are always at play.

On my old Honda CRZ I did run the same 1.5 hour trip over and over again, hundreds of times throughout several years, and I was aiming for top MPG each and every time. I never did test regular fuel or premium, only ran 89 mid-grade for 66 thousand miles. I was top 1% of fuel economy average reported the entire time I owned that car, but literally every other condition was set up to promote my success as well so I can't attribute it to the fuel, I was simply a constant hypermiler operating in perfect conditions. My only hope for the mid-grade fuel was that it would hopefully be cleaner and keep my fuel system sparkling for as long as possible, since there was no user-replaceable fuel filter in those cars.
 

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Discussion Starter · #5 ·
I realize octane has little if any effect on modern engines. However, premium fuels, from a quality brand will have additives that benefit the fuel system in other ways. I had a 10c discount at Irving so I just filled up with 93. I'll be curious to see if it's at least in the same league with the non-ethanol premium.
 

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I can attest to better mileage with non-ethanol gas. Many trips to Oklahoma from Ohio in my old Liberty, average 18.5mpg with blended gas. On the way home with pure gas (the way it is supposed to be made) was >22mpg - this gas is readily available at many OK stations. When I had to put blended crap back in the tank, then the mileage went back down to sucky. Find a pure gas station

All about octane
 

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Return trip comparisons like that are problematic because it's rarely flat between two points. For example, if we drive from where we are in Minnesota to our favorite camping spot in Wisconsin the terrain varies but it's overall a slightly uphill drive (gaining elevation) for 6 hours. We always get better mileage coming home on those trips when it's trending back downhill. We've seen this problem going from MN to the west coast as well due to wind. When we are heading west we tend to be driving into the wind, when we come back home more often than not the wind is in our favor. In both cases there is a 2-3 mpg difference in fuel economy going vs coming back.

Have to be careful not to mistakenly come to an errant conclusion such as "the gas is better in Wisconsin because I get better gas mileage when I buy gas out there and drive back", get what I mean? It's a dumb example but my point is that it's very difficult to make an accurate test out in the wild due to all the other factors going on.

When I had my hybrid Honda and I was big into playing MPG wars with other owners, and I was doing the same 1.5 hour trip over and over for two years twice a week, one way was more downhill and I'd run up an MPG average over 50 mpg (car was rated for 37 or 39), then on my return trip more uphill it would take every bit of concentration I had not to let that number slip under 48 by using momentum to coast up hills and the like. I had fun with that but I don't have the interest in wringing every last MPG out of this Compass. I did make that 1.5 hour journey once in the Compass back when I first got it and pulled 38 MPG for the first leg of the trip, a truly great figure for this car but I'd driven the road for max mileage so many hundreds of times before it was pretty easy. That number fell apart with in-town driving and the uphill return trip of course but it was fun for a while.

But anyways, it's awfully hard to prove anything outside of lab or track environment due to the small 2-3 mpg numbers at play being so easily effected by other conditions like weather and elevation and even other factors beyond that. Thousands of test miles driven as close to the same as possible you could still have 2-3 mpg tipped by the other factors, so keep those in mind when making claims and assertions about MPG.
 

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Return trip comparisons like that are problematic because it's rarely flat between two points. For example, if we drive from where we are in Minnesota to our favorite camping spot in Wisconsin the terrain varies but it's overall a slightly uphill drive (gaining elevation) for 6 hours. We always get better mileage coming home on those trips when it's trending back downhill. We've seen this problem going from MN to the west coast as well due to wind. When we are heading west we tend to be driving into the wind, when we come back home more often than not the wind is in our favor. In both cases there is a 2-3 mpg difference in fuel economy going vs coming back.

Have to be careful not to mistakenly come to an errant conclusion such as "the gas is better in Wisconsin because I get better gas mileage when I buy gas out there and drive back", get what I mean? It's a dumb example but my point is that it's very difficult to make an accurate test out in the wild due to all the other factors going on.

When I had my hybrid Honda and I was big into playing MPG wars with other owners, and I was doing the same 1.5 hour trip over and over for two years twice a week, one way was more downhill and I'd run up an MPG average over 50 mpg (car was rated for 37 or 39), then on my return trip more uphill it would take every bit of concentration I had not to let that number slip under 48 by using momentum to coast up hills and the like. I had fun with that but I don't have the interest in wringing every last MPG out of this Compass. I did make that 1.5 hour journey once in the Compass back when I first got it and pulled 38 MPG for the first leg of the trip, a truly great figure for this car but I'd driven the road for max mileage so many hundreds of times before it was pretty easy. That number fell apart with in-town driving and the uphill return trip of course but it was fun for a while.

But anyways, it's awfully hard to prove anything outside of lab or track environment due to the small 2-3 mpg numbers at play being so easily effected by other conditions like weather and elevation and even other factors beyond that. Thousands of test miles driven as close to the same as possible you could still have 2-3 mpg tipped by the other factors, so keep those in mind when making claims and assertions about MPG.
Yep, all understood. Not a test track, not controlled, variables, etc. etc. The area that I use as 'my' test track is I-44 from Joplin to Tulsa to OKC. I have driven that stretch 23 times since 2004. Joplin's elevation is 1004', Tulsa is 735', OKC is 1201' - up hill/down hill pretty much evens out coming and going.. It is usually windy, cross wind between Joplin & Tulsa, head wind from Tulsa to OKC, tail wind from OKC to Tulsa. Speed limit is 75, 3 stops from Joplin to OKC. Under any conditions my Liberty never got more than 18.5 MPG, except when running pure gas from OKC to Joplin when I consistently hit above 22 MPG. Fill up at Joplin 44 and then I could watch the mileage drop back to 18-ish.
YMMV:)
 
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