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I apologize for asking this in an Insight forum, but I can't find a Civic Hybrid forum to ask this and I figured you Insight guys would probably have an answer... (I also searched but didn't see this addressed directly)

I bought a 2005 Civic Hybrid in late November and was getting 47 mpg on "regular" grade gas (86 octane).

I was curious what kind of difference a higher octane might produce since the Civic Hybrid has a high-compression engine so I put tank number three in with 88 octane.

I'm now showing 54.1 mpg with 210 miles so far on this tank. This is higher than the EPA rating which is surprising to me. Also, I'm not babying the car and am actually speeding a bit (mostly highway for that 210 miles and 65-70 mph). These are round trips too so it's not like I've just been driving down hill.

So I was wondering, have you guys experimented with higher octane to help mileage? Does the Insight use a high-compression engine where the octane might allow the engine to develop more power and get better mileage? Anyone else seen this dramatic of a difference by upping the gas a grade?
 

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There have been discussions in here in regard to MPG & Octane, but their mixed in with other posts and rather old.

AFAIK the Civic hybrid has a knock sensor. If this is true then a higher octane will allow improved MPG. However, its usually not "cost effective" in that the increase in MPG does not offset the increase in price. But there are other potential _long term_ benefits to higher octane, the minimal difference in detergent additives and carbon build-up. Specifically EGR port clogs. There are _many_ factors that can effect these type of "problems" so as always YMMV, especially in this regard.

With the Insight its been shown that when using low sulpher brands of fuel emissions are improved to be equivalent of ULEV (often premimum grade). The 5 spd. Insight is only LEV. So there are "green" benefits too!

HTH! :)
 

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You say your on tank #3, I would be willing to bet that your mileage incrase has a lot more to do with the vehicle being more broken in than anything. To be scientific about it you should really wait till you have at least 5000 miles on the car before drawing any conclusions. That said, the higher compression ratio is deffinitely more compatible with higher octane fuel. The Insight service manaul says something to the effect of for best mileage and performance use 91 or higher octane fuel. In fact with the Insight the US owners manual is the only one that suggests using 87 octane only. The German, UK, Japanese ones all say to use the equivelent of 91 octane.
 
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Hi Refields:

___The i-DSI in your HCH was designed to avoid knock at a higher compression ratio on Regular Unleaded do to its swirl and dual spark per stroke. Second, knock usually comes about at higher loads (fast accelerations) and if you are anywhere near those, you will definitely not be worried about FE. Running Regular unleaded in the Acura MDX (91 Octane Premium recommended per the manual), the KS pulls back timing but it is only at or near WOT or when towing in higher temperatures. As it stands, the highest FE ever achieved while driving an Insight or MDX has come on regular unleaded so using Premium is throwing $2.00 and $4.00 on the ground and burning it at each and every fillup depending on which car is fill. Higher fuel economy does not come about from using higher Octane fuels in your HCH.

___Insightful Trekker, the only reason some higher Octane fuels produce less emissions is because they are lower in sulfur. BP/Amoco Ultimate in the Chicago area is 30 ppm or less whereas the regular and mid-grade are as high as 3 - 500 ppm thus the LEV rating vs. ULEV on the two types of fuels. In California for example, all fuels are 50 ppm or less and thus the Insight has a ULEV emissions rating no matter which grade you use there. The Detergent packages are federally mandated to meet a certain test requirement and this comes in all grades.

FTC - Facts for the Consumer

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:2uqmur9a][email protected][/email:2uqmur9a]
 

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I have had the exact opposite response of the other posters, in line with the original poster's experience.

With non OEM tires and Mobile 0w oil I notice a huge difference between reg grade and premium grade gas, specifically in the engine power, fuel economy, and lean burn window. I just drove over 120 hrs in my Insight for well over 7,500 miles and found that in mountainous terrain, using premium gas made getting up steep hills much easier.

The performance was worth the cost.

My wife owns a HCH and on our last trip (approx 8k miles) we used premium often in higher elevations and mountainous regions for the same reason. You're not alone... lol.

-Philosophy
 

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Discussion Starter #7
Thanks for the replies and hopefully this fits well enough with Insights to be ok. As suggested I will head off to the Yahoo forums and see if I can find other Civic Hybrid owners there.

As to the improvement being due to break-in of the engine/drive train, this was a step function. The Civic Hybrid has instantaneous as well as aggregate trip mileage functions. The first two tanks held very steady at 47 mpg. There was no appearance of it trying to creep up as I was nearing the end of tank two.

It might be that it's getting more broken in but I don't think so. With the innformation that the hybrid has a knock sensor and I would guess retards timing when it senses knock, and especially since they want you to keep the revs low with the shift indicators, I'm thinking the regular gas around here isn't so great and that the timing was retarded to prevent knocking and that may have led to lower mileage.

But regardless, to now be getting 7 mpg better mileage and having that be above the EPA estimate is bit surprising to me. Also, the 7 mpg improvement is the equivalent of a $0.30 price difference in gas at $2.00/gallon and 88 octane is only about $0.10 more than regular here - so I'm going to be buying 88 octane from now on.

Sorry to have butted in here and I'll go see about finding Honda Civic owners elsewhere.
 

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refields said:
<snip>

It might be that it's getting more broken in but I don't think so. With the innformation that the hybrid has a knock sensor and I would guess retards timing when it senses knock,

<snip>

Sorry to have butted in here and I'll go see about finding Honda Civic owners elsewhere.
The break in period happens for both the driver and engine. <g>

AFAIK most HCH MPG indicators read 5%+- optimistic whereas Insights are rarely more than 1-2% off long term calculated averages.

Most people misunderstand the knock sensors function. Its exactly opposite. It _advances_ timing to the knock tolerant point. Yes timing will be more "retarded" with lower octane fuel and under many driving conditions power and MPG will be less.

Please don't feel you "butted" in. Its just that you'll likely get much better HCH specific responses from an HCH group.

The Insight and HCH are close cousins after all! :)
 
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Hi Refields:

___There are quite a few HCH drivers over at Greenhybrid that really push the FE envelope and none that I know of are running premium unleaded. It simply is a waste of money. They may have answers for other questions that you may have now or in the future as well.

___Philosophy, as a counterpoint, most mountain communities regular is 86 Octane. As you climb, the lower pressure is a pre-detonation suppressor so you don’t need as high an Octane fuel at higher elevations even in automobiles that require 91 Octane premium unleaded.

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:278wlgu4][email protected][/email:278wlgu4]
 

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Counterpoint taken.

In Utah the "Regular" gas is sold at 85 Octane in certain locations (several of the places I stopped). I think that is because people who live there will probably see some advantage or it is unnecessary or costly to have the full octane that most places generally have, but my point is not related to what is best for living in a mountainous community. My point is that my Insight (with its specific running, tires, etc which vary from your individual experiences) gets way more kick out of premium gas, which in many states is only marginally more expensive than regular. Consider Nebraska for example, where premium gas only costs 2-10 cents more per gallon than regular; there is no reason not to buy it thanks to the other benefits in addition to superior performance. It makes it easier to get to mountainous communities in the first place, that's my point of view.

I know hypermilers do their own tests in perfect circumstances etc and use unleaded fuel, they also drive in very unrealistic circumstances (flat land? hah) compared to most daily driving experiences. I most also say that my Insight was very loaded down with probably close to 800 lbs of people and stuff in it. I know that was severly breaking the rules but hey, at least I know I could do it in the future and (maybe) get away with it.
 
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Hi Philosophy:

___I know a hypermiler that resides in Washington state and travels across Utah more then once or twice a year. Billy, do you remember the name of that guy? I know a Hypermiler that lives in California although I don’t know his specific commuting terrain. CalPod, do you know who I am speaking of? I know another Hypermiler that lives in the Carolina’s and travels up to D.C. and back once a week. Rick Reese, you might have heard of that guy, right ;) Chisight and I have Northern Illinois just about covered. Yes, I would say that about covers most of the country. All of these guys use Regular Unleaded that I know about? As for loaded down, yes, I have taken my son back to the University of Illinois more then once in the Insight with it loaded to well beyond capacity last Winter/Spring. I remember a 94 mpg round tripper when it was still below 50 degrees. I also remember a high 60/70 mpg trip home one night with a 30 to 40 mph headwind? I even posted about it here at InsightCentral after it was all over. I will have to find that one? All the while using Regular Unleaded. You can use whatever you wish because Premium should not cause your Insight any harm but as far as FE is concerned, you are not receiving any more on it then with 87 Octane in my experience.

___Have you read the Car and Driver test where the Accord they were dyno’ing actually received less HP while running 91 octane fuel? I can provide the link with a few minutes of searching if you would like?

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:257egdi7][email protected][/email:257egdi7]
 

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I live in WA but cruise I-15 through Utah at least 8-10 times per year. In my area, supreme is 22 cents higher EACH GALLON. I always use 87 oct regular; I consider it a waste of $ to use supreme. Billy.....
 

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xcel, I'm surprised by your very passive aggressive post.

I have to say that the only way people get FE like that is to just plain drive slow. I understand that if you want max FE you're going to have to sacrifice acceleration and some speed to keep it that high, myself, I would prefer to drive at or slightly above the speed limit (70-75) which means downshifting for hills and utilizing the assist pack to get up hills and maintain a constant rate of speed or slight deceleration.
I don't think there's anything magical about getting really high FE by overpressuring your tires, accelerating slow, and moving below the posted speed limits or on roads with lower speed limits and superior terrain. My personal experience is that premium gas provides more power. It helps me maintain speed going up steep inclines, and also helps fuel economy by seemingly increasing the size of the lean burn window. Your experience may vary, and that's fine. At home I don't need to use premium to get the performance I want, and usually don't pay the extra cost for it, but it often does help in varying terrain to have some higher octane in the tank.

-Philosophy
 
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Hi Philosophy:

___Passive is not what I have been known for but being a straight shooter is …

___Mind telling me what your lmpg and segment mpg’s are driving 70 - 75 mph in your terrain?

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:3iurwi9z][email protected][/email:3iurwi9z]
 

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Ok xcel,

So where can you go with this? Higher octane rated fuels when used with knock sensor equipped cars and under certain driving patterns / conditions will get slightly better MPG. I've objectively proven it to myself.

Now if I lived in the flatlands and drove in the hypermiler style I would believe you simply based on your experience. <sincerely>

[EDIT: "believe not" - "believe you". It was a poorly constructed statement. And is my final "word" on this subject.

See you in another thread :) ]

And by your _own_ admission at least one oil company reserves its low sulphur blend to premimum fuel. Which has known beneficial effects for our cars and the environment.

So maybe its best to stop while your ahead?
 
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Hi Insightful Trekker:

___> 11,000 members over at AcuraMDX.org and at least 95% or more are using Premium unleaded (Acura recommended). Not a single one has ever hit > 28 mpg in an MDX. I usually attain > 30 driving 58 - 63 mph on Regular unleaded w/ a high of 33.1 (I was at 34.7 when the temps started falling away on me) with the last 80 miles in temps below 60 and a final low of 53 degree F.

http://www.acuramdx.org/forums/attachme ... tid=231413

___Could I have achieved higher FE with 91 Octane Premium? No but I would probably not achieved worse either. Those driving without their foot in the floor cannot take advantage of Premium unleaded even in an automobile designed for it and if you are a FE driver, you most certainly are not driving with your foot to the floor. We (MDX owners) have had the Octane debate discussion rolling for years and this is in a vehicle that at WOT actually achieves another 5 % or so HP on Premium vs. Regular unleaded. FE however doesn’t increase in the least for anybody using Premium over and above regular in this automobile.

___There are more then 1,050 members here at Insight Central and most if not all the hypermilers fuel of choice is Regular unleaded. Chisight runs BP/Amoco Premium unleaded to hopefully remove any poisons from his CAT every fifth or so tank (he has had 2 replaced in the last 15,000 miles on Honda’s dime) and has seen no benefit in FE.

___It is one thing to talk performance improvements; it is an entirely whole other matter to speak of FE improvements while running Premium in car meant for Regular. Here is that Car and Driver Article I was speaking about above:

Regular or Premium

But, noted Schiller, only a few vehicles calibrated for regular fuel can advance timing beyond their nominal ideal setting when burning premium.

High altitude reduces the demand for octane.

The Accord took a tiny step backward in power (minus 2.6 percent) and performance (minus 1.5 percent) on premium fuel, a phenomenon for which none of the experts we consulted could offer an explanation except to posit that the results may fall within normal test-to-test variability.

Our tests confirm that for most cars there is no compelling reason to buy more expensive fuel than the factory recommends, as any performance gain realized will surely be far less than the percentage hike in price.
___Just about any page on the web discussing this topic has stated that a car designed for regular unleaded will not achieve higher FE or power when running Premium unleaded.

___Did you want to go further with this?

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___[email:xeq8sbfq][email protected][/email:xeq8sbfq]
 

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Most vehicles that require Premium fuel are "Performance" vehicles, Premium fuel is only good when you are heavy on the gas pedal, but if you are not, it's not requiered.

I have some vehicles that require Premium fuel, and since I've changed my driving habits drastically, I no longer see the need for Premium fuel, on a trip from LA to San Diego, I recently achieved 47 MPG on my 1999 Civic SI running regular fuel.

This is the highest I've achieved on a non-hybrid vehicle ever, as for the Insight, I don't think the extra cost of premium is worth the .005 mpg increase. LOL
 

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>>Premium fuel is only good when you are heavy on the gas pedal, but if you are not, it's not requiered.

Like when you're going up the side of a mountain. Last year we drove to Sequoia National Park, straight up from approx 500 ft elevation to over ~9k elevation in our HCH, it required flooring it in many places just to continue at current speed (approx 45 mph) and completely drained the pack, probably the most difficult driving we've ever done in that car. This year in the Insight we drove up a mountain pass in Oregon going from 500 elev to about ~7k with premium in it, and I maintained a charge and speed and even got lean burn in the less angled portions of the road. The difference is night & day.
 

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Does anyone else get worried to drive there insight into interstate my steering scares me at that speed is it normal or do I need get something checked on my car
 
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