Amazing MPG Improvement Without Corn (N/A)

RJM62

RJM62

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Geek on the Hill
So the "winter blend" gasoline has started flowing, and predictably, the MPG in my newest car (2012 Kia Soul) dropped by 8.62 percent, from an average of 34.8 MPG to 31.8.

I had to make a long-ish trip today, and as it happens, I was near a gas station that sells corn-free premium when I was down to a little over 1/4 tank. So I filled up on the corn-free, making for a tank mix of 3/4 corn-free 91-octane to 1/4 corn-laced 87-octane. Then I started the trip home, a long trip on a winding, hilly mountain road that passes through a couple of sleepy villages -- not exactly a hypermiler's paradise.

By the time I got home, the car's computer was reading an average MPG of 42.5 MPG on the ethanol-free premium, compared to 31.8 on the "winter blend" corn-laced regular, or an improvement of 33.65 percent.

Cost-wise, given the above figures and the current prices, the corn-free still costs about $0.008 more per mile than the corn-laced. On the other hand, the car performed better (for example, hills that I usually take in third, I could take in fourth); and assuming a reserve of about a gallon, the corn-free also adds about 118 miles range per tank of gas.

I'll probably fill up with 91-octane corn-laced next time so I can get a fairer comparison. The 33.65 percent improvement in MPG is comparing the highest (and only, around here) grade of corn-free with the lowest grade of corn-laced.

Rich
 
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A couple years ago we were on a long driving vacation. At one of the gas stops we were able to fill up on pure gas. At our next stop I was very happy with the increased mileage, and not happy at all that I couldn't get pure gas more often.
 
The OP's figures coincide with mine concerning MPG in a 2009 Hyundai Elantra. Having checked everything from tire pressure, tire size, engine performance, engine accessories, the only thing remaining is fuel quality to explain the mileage drop. This is in SoCal and involving regular driving over same routes.
 
Matthew said:
A couple years ago we were on a long driving vacation. At one of the gas stops we were able to fill up on pure gas. At our next stop I was very happy with the increased mileage, and not happy at all that I couldn't get pure gas more often.
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The way you say that reminds me of a certain Charlton Heston SciFi movie.

"Well, we got Soylent Orange."

"No, I want the good stuff. Gimme the Green. And it better be the good stuff."


Of course, those lines weren't in the movie. I can write my own script...unless it is in reality.
 
Missouri has E10. Every vehicle I own gets over 10% less gas mileage on E10 than it does on "real" gas.

So what are we gaining again?
 
Re: Amazing MPG Improvement Without Corn (N/A)p

We are gaining nothing except higher food prices, I will leave the high fructose drama for somebody else.

It is just another handout to the farm lobby.

Also the e10 gasoline isn't as friendly to the internals of your car, newer ones might be engineered for it, but it still has more moisture in it. This debacle can legitimately be blamed on Bush.
 
I rarely buy gas these days. As long as I can stay under 42 miles I run on a mix of coal, natural gas, and nuclear power. Almost all domestically produced and at about a third of the carbon footprint.
 
That's pretty amazing given that the actual difference in the heating values of the two fuels less than 10%.
 
timwinters said:
Missouri has E10. Every vehicle I own gets over 10% less gas mileage on E10 than it does on "real" gas.

So what are we gaining again?
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More expensive food and subsidies for farmers. Probably the best thing we're getting is that the ethanol biz isn't what it used to be, several people who have tapped out and are now opening up distilleries.
 
>> car performed better (for example, hills that I usually take in third, I could take in fourth)

Clear evidence that the higher octane was making a difference in your vehicle. That's a separate decision than ETOH or no ETOH.


Paul
 
I see better milage using plain old ethanol-free 87 octane cheap gas than anything with ethanol.
 
Capt. Geoffrey Thorpe said:
That's pretty amazing given that the actual difference in the heating values of the two fuels less than 10%.
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I have often seen this assertion, but I can absolutely confirm that I had very similar results during the time when we could still find uncontaminated gasoline here. The difference in gas mileage was substantial when the ethanol-containing gas was used, typically 8-12% lower.
 
Do a hand calculation. Don't use the computer. Calculated the cost of fuel per mile, not MPG.
 
Dan Thomas said:
So what fuel does the OP's Kia need?

In a vehicle that has higher compression, a low octane fuel will cause knocking. The engine's knock sensors will retard the timing, affecting both power and economy.

Dan
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I think we can both agree the knocking would occur at high loads.... Even engines that "require" 91 octane in automobiles can safely run 87.
 
Dan Thomas said:
So what fuel does the OP's Kia need?

In a vehicle that has higher compression, a low octane fuel will cause knocking. The engine's knock sensors will retard the timing, affecting both power and economy.

Dan
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87 octane per Kia and I'll go out on a limb and guess the OP has not upped the compression.
 
Maybe the fact that gasoline has 114000 BTU's of energy per gallon and ethanol has 76100 BTU's of energy per gallon has something to do with it.
 
What is this? Some sort of Pro-Terrorism thread?
:D
 
30+% is not plausible. Too many variables.

Ethanol does hurt mileage, but not nearly that bad unless you actually used E85.

I see 10% variation in the mountains using the SAME fuel. It can be a lot worse if I get stuck behind a tourist.
 
lowtimer said:
Maybe the fact that gasoline has 114000 BTU's of energy per gallon and ethanol has 76100 BTU's of energy per gallon has something to do with it.
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So E10 would have 110,210 BTUs by your figures. Not NEARLY the amount to account for a 30% change.:dunno:

“Reality leaves a lot to the imagination.”
― John Lennon
 
timwinters said:
Missouri has E10. Every vehicle I own gets over 10% less gas mileage on E10 than it does on "real" gas.



So what are we gaining again?
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Can't answer that without moving thread to spin zone
 
kgruber said:
So E10 would have 110,210 BTUs by your figures. Not NEARLY the amount to account for a 30% change.:dunno:

“Reality leaves a lot to the imagination.”
― John Lennon
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I'm with you on the 30% change being more than can be accounted for by the change in energy potential. What I don't buy is that putting 91 octane in an 87 octane rated motor caused a 30% increase. If I had to guess it has something to do with the way the computer is figuring the average at the end of this trip.
 
flyingron said:
I rarely buy gas these days. As long as I can stay under 42 miles I run on a mix of coal, natural gas, and nuclear power. Almost all domestically produced and at about a third of the carbon footprint.
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Maybe this should be a new thread, but I'd like to hear more about electric cars. I've been waiting to jump in until they get 100+ mile range, but I'm getting antsy.
 
flyingron said:
I rarely buy gas these days. As long as I can stay under 42 miles I run on a mix of coal, natural gas, and nuclear power. Almost all domestically produced and at about a third of the carbon footprint.
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I rarely buy gas also I buy diesel. Same problem with diesel different states have different % of bio diesel required.
 
bnt83 said:
I think we can both agree the knocking would occur at high loads.... Even engines that "require" 91 octane in automobiles can safely run 87.
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Generally I'm pretty easy on the pedal in my '05 BMW 530i. Are you saying I could run the "cheap stuff" without fear of knocking if I don't put a load on it?

Update: I just went to Car Talk's website and they actually have some pretty good information about it. Thanks POA, you just saved me the cost of my subscription! :D
 
kgruber said:
So E10 would have 110,210 BTUs by your figures. Not NEARLY the amount to account for a 30% change.:dunno:
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There is also a density difference. But...

Fuel economy is a real hard thing to measure.

I used to do it for a living. And, even with a single car, with a carefully specified fuel, running the same drive cycle, while analyzing the chemical concentrations in the exhaust using constant volume sampling, you get several percent variation. Things like robot drivers, doing all of the testing on the same dyno cell, checking the tire pressure with the same gauge before each test, controlling the start times so you get the same cool-down period between each test, and a bunch of other things I forgot help enough that you can detect changes on the order of 3%-5% or so with only a handful of tests. On the road testing is pretty much a waste of time. On the road testing where the driver knows what the outcome should be is even worse.
 
Dan Thomas said:
So what fuel does the OP's Kia need?

In a vehicle that has higher compression, a low octane fuel will cause knocking. The engine's knock sensors will retard the timing, affecting both power and economy.

Dan
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If the engine has a knock sensor... If not?

Some manufactures optimize the engine for premium fuel to get better fuel economy labels even though the cost of the premium outweighs the improvement in fuel economy.

Label trumps customer cost.

As of when I retired, Ford did not do this (dunno about Kia)- Ford optimized for regular so running on premium would get you nothing. But even then, some engines (but not all) had knock sensors to let them get as close to the edge as possible on regular.

Look at the owners manual. If it says "use premium" use premium. If it says "Premium recommended" then you can expect some loss of fuel economy if you run regular. If it recommends regular, run regular - period.
 
lowtimer said:
The higher octane will not improve mileage or performance in a vehicle designed to use 87 octane. http://www.consumer.ftc.gov/articles/0210-paying-premium-high-octane-gasoline
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Except that no car I've ever owned has cared very much about the FTC's opinion on the matter. Nor do I, for that matter. You apparently haven't read many of my posts if you think I give a rat's ass one way or the other what any government agency has to say about any possible topic. :no:

I will say this much, though: Octane rating itself has little to do with fuel economy. Other than preventing the spark from being retarded quite so often, octane and fuel economy are not related. So if you want to take a strictly literal interpretation of FTC's position, they're right.

Now back to the real world.

Octane may have almost nothing to do with fuel economy, but BTU content most certainly does; and higher-octane fuels usually have higher BTU content. They don't have to, by the way. You can spike octane rating with many different chemicals that have low energy density (including ethanol). But in practice, the higher-grade fuels usually are more energy-dense; and energy density most certainly affects MPG.

I haven't owned the Kia long enough to have its economy down to a science, but in each of the previous five cars that I've owned since I started tracking MPG (all of which called for 87-octane), the cost-per-mile has always been lowest using 89 octane. There was a significant MPG increase from 87 to 89, a little bit of improvement from 89 to 91, and no improvement at all from 91 to 93. But because of the price differences, the 89 was the most cost-effective. (I'm just using the octane numbers for convenience, by the way. MPG has almost nothing to do with octane.)

By the way, I put another 54 miles on today, and the current reading is 39.6 mpg, down from 42.5 yesterday. That's to be expected on a cool, wet day. Lower temperatures and wet roads both decrease MPG. But it's still a lot better than 31.8.

My next fill-up will be with corn-laced 91 octane for comparisons' sake. I'm not going to bother with the 93 because I suspect that the octane is bumped up to 93 with some high-octane / low-energy additive, based on the fact that it's never yielded any MPG improvement over 91 in any car I've owned.

Rich
 
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I had (no longer have) about 90,000 miles worth of records from my 2001 Deville, and the correlation between corn-contaminated fuel and significantly lower gas mileage was absolute and repeatable.

The Deville burned regular unleaded (it was the first year they did not recommend premium for the Northstar); on occasion, I ran premium (where I could get premium no-corn in lieu of regular, but contaminated, fuel ), and there was no measurable change in mileage, nor noticeable change in performance.

The ethanol in fuel destroyed the fuel pump in my Eldo.
 
Those instant read MPG displays do show interesting results. When I drive on the highway at home (1000' MSL) vs where my folks live (>8000' MSL) I see some big differences. I know the octane ratings are slightly different, but not that much. Air density really comes into play, probably way more than octane and ethanol.
 
RJM62 said:
Except that no car I've ever owned has cared very much about the FTC's opinion on the matter. Nor do I, for that matter. You apparently haven't read many of my posts if you think I give a rat's ass one way or the other what any government agency has to say about any possible topic. :no:

I will say this much, though: Octane rating itself has little to do with fuel economy. Other than preventing the spark from being retarded quite so often, octane and fuel economy are not related. So if you want to take a strictly literal interpretation of FTC's position, they're right.

Now back to the real world.

Octane may have almost nothing to do with fuel economy, but BTU content most certainly does; and higher-octane fuels usually have higher BTU content. They don't have to, by the way. You can spike octane rating with many different chemicals that have low energy density (including ethanol). But in practice, the higher-grade fuels usually are more energy-dense; and energy density most certainly affects MPG.

I haven't owned the Kia long enough to have its economy down to a science, but in each of the previous five cars that I've owned since I started tracking MPG (all of which called for 87-octane), the cost-per-mile has always been lowest using 89 octane. There was a significant MPG increase from 87 to 89, a little bit of improvement from 89 to 91, and no improvement at all from 91 to 93. But because of the price differences, the 89 was the most cost-effective. (I'm just using the octane numbers for convenience, by the way. MPG has almost nothing to do with octane.)

By the way, I put another 54 miles on today, and the current reading is 39.6 mpg, down from 42.5 yesterday. That's to be expected on a cool, wet day. Lower temperatures and wet roads both decrease MPG. But it's still a lot better than 31.8.

My next fill-up will be with corn-laced 91 octane for comparisons' sake. I'm not going to bother with the 93 because I suspect that the octane is bumped up to 93 with some high-octane / low-energy additive, based on the fact that it's never yielded any MPG improvement over 91 in any car I've owned.

Rich
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I was not replying to you and the link was just one of many that say about the same thing.

I'm having a hard time finding anything that says that higher octane fuels usually have higher BTU content, source please? (and lets keep it "pump gas" as we are not discussing race or specialty fuels) On the other hand I am finding many reports of people seeing a couple MPG increase on premium vs regular so maybe there is something to this.

30+% increase has me thinking there is more going on than 87-91 octane or summer vs winter blend.
 
I have a 30 minute drive each way to the airport. It is 95% highway and cruise control

The difference between non-ethanol and ethanol fuel is 15-18%. A gas station right down the street sells non-ethanol so I have run a few tanks through my car and recorded the MPG
 
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I think somebody didn't take science and sampling classes.
 
lowtimer said:
On the other hand I am finding many reports of people seeing a couple MPG increase on premium vs regular so maybe there is something to this.
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Might be that premium is non-ethanol. One gas station here had premium non-ethanol fuel. It wasn't labeled, you wouldn't have known unless you tested it. I used to run it in a 152 that had an STC
 
Down here in Costa Rica there is no corn juice and reg is 91 and super is 95. I have an escalade that recommends premium and a Porsche that takes 95 octane. The prices for a gallon down here are super=$5.80, regular=$5.56, diesel=$4.91(diesel is not the same quality as US). I see no difference when I run super in the Escalade.
 
BTU content will not vary with octane rating in a given group of fuels. Even very high racing fuels (gasoline) will have no appreciable BTU difference, flame temperature or combustion speed. Exception: some gasoline designed for racing applications, high RPM and compression, may have a slightly higher speed of combustion.
Mathematically, gasoline with 10% ethanol will have about 5% less energy per unit. I do not see how you can increase mileage more than the BTU content difference.:dunno:
 
ronnieh said:
BTU content will not vary with octane rating in a given group of fuels. Even very high racing fuels (gasoline) will have no appreciable BTU difference, flame temperature or combustion speed. Exception: some gasoline designed for racing applications, high RPM and compression, may have a slightly higher speed of combustion.
Mathematically, gasoline with 10% ethanol will have about 5% less energy per unit. I do not see how you can increase mileage more than the BTU content difference.:dunno:
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I know many race fuels are oxygenated and I guarantee that they have a higher BTU count.
 
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