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25%+ increase in milage <SNAP> - SUNOCO ULTRA 94

9491 Views 31 Replies 16 Participants Last post by  Insightful Trekker
This is my first post here. The reason is, I have had nothing to contribute since getting my brand new 2004 CVT several months ago and visiting this site prior to this. But the time has come!

The weather here in NJ has been in the mid to low 40's for some time now and continues in this range. My mileage has been 50 - 52 mpg during this time.

Last week it was time to fill the Insight up. Having read a number of posts here regarding premium fuel, both pro and con, I thought I would give it a shot. I filled it up with SUNOCO ULTRA 94 octane and reset my FCD. After about 75 miles of driving the MPG was stabilizing between 68 - 70 MPG! After another week of driving 300+ miles, the MPG remains the same, 68 - 70 MPG! No difference in temperature, no difference in driving habits or terrain, essentially no difference at all... except the fuel.

Now I understand that there are all sorts of varying opinions regarding this issue, many with what seems to be a good 'scientific' basis or reasoning as to why this mileage increase can not be attributed to the type of fuel. But facts are facts. And I must engage in a psychotic break with the interpretation of reality to deny that use of this particular fuel does not have a dramatic effect on the increased mileage of the vehicle.

I would suggest strongly the use of SUNOCO ULTRA 94 to increase the MPG, or at least try it. For those who may use this fuel and do not have such success, you too must face the reality of your experience, but I would suspect that it has something more to do with engine performance issues than the fuel. Keep in mind, my vehicle is brand new (7.5K miles to date).
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Where are you located that you have 94 octane fuel? The regular grades available to me are 87,89 and 91 (used to be 92, but that was before I could drive).

I know in the past I've always said use premium, but this last week I filled with 87 just for a change and I gotta say I haven't noticed any difference (there... I said it).

Still, the service manual says something to the effect of for best mileage and performance use 91 or higher octane fuel. I think there would be slightly less difference with the CVT with it's lower compression ratio. I wounder what the CVT non US owners manuals say. I believe the German, Japanese, and UK owners manuals say to use whatever their equivelent to 91 octane is. I think in the end YMMV is just something to stick to.

Continuing to ramble on here, I think if there is any difference in mileage it's deffinitely not enough to offset the higher cost of premium fuel.
The us manual says 87 octane, the rest of the world's suggests higher. As far as I know there is no major difference in the drive train's umong different sections of the world. The Insight's knock sensor is more than capable of adjusting the timing for 87. You don't need to use premium.

This should explain it better: ... ml#GasType
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