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ycr99

Grade Of Gas

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Right. Based on that figure I'm guessing you drive an automatic.

That is true. Manual would be better?

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trap

Octane isn't linked to energy content of the fuel. As long as the fuel meets the octane requirement of the car, energy content will determine MPG.

 

For example, methanol has an octane of 115 (R+M/2), but gives half the MPG of non-oxygenated gasoline (i.e., if a Corolla engine could run on pure methanol). Ethanol has an octane of 113, but has 65% of the energy content of a non-oxygenated gasoline. (this is true for any car)

 

Higher octane is only needed when an engine pings - at that point, higher octane will help performance. However, when I sold my 1989 Corolla w/120K miles, it still did fine on 87 Octane.

 

As noted, the Corolla's engine was designed for 87 Octane. The car's computer can compensate for higher octane, but you're pushing the car outside it's optimum.

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That is true. Manual would be better?

 

 

True. Manuals are rated at a higher MPG than automatics.

Why do they burn less fuel? Are people faster at shifting than an automatic?

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That is true. Manual would be better?

 

 

True. Manuals are rated at a higher MPG than automatics.

Why do they burn less fuel? Are people faster at shifting than an automatic?

 

 

Manuals get better fuel ratings because the car is upshifted at low RPMs, lower RPMs than the auto shifts at. However, if you drive a stick an don't upshift at low RPMs, but upshift at higher RPMs than the automatic, you will get worse fuel economy.

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That is true. Manual would be better?

 

 

True. Manuals are rated at a higher MPG than automatics.

Why do they burn less fuel? Are people faster at shifting than an automatic?

 

 

Manuals get better fuel ratings because the car is upshifted at low RPMs, lower RPMs than the auto shifts at. However, if you drive a stick an don't upshift at low RPMs, but upshift at higher RPMs than the automatic, you will get worse fuel economy.

 

So the advice for people with standards would be to shift early and it will save them some fuel and improve gas consumption?

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Yes Bikeman, shifting at lower RPMs results in greater fuel economy. I can personally attest to this. My Mazda has two driving modes, full auto and semi auto. In full auto it works just like any other automatic. In semi-auto, the car doesn't shift itself. This is like a manual but without the clutch, meaning you MUST shift it, it will not up-shift for you. If I leave the car in full auto it gets 33 MPG highway. If I go semi auto and keep shifts below 2500 RPM, I get ~36 MPG highway. If I drive as I normally do, which is upshift from 1st to 2nd at 5200 RPM, 2nd to 3rd at 5000 RPM and 3rd to 4th at 4500 RPM, I get a pathetic 27 MPG highway. A true manual transmission would yield the same result.

Edited by the99contour

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Speaking of RPM's, I have a 2002 Corolla with automatic. In high gear, I'm at 2000 RPM at 65 MPH. Does that seem right?

 

I'm still trying to figure out why I'm only getting 30 MPG driving mostly highway. I have 185 size tires which are a little taller than 165. I wonder if and how this effects the MPG also.

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Yes Bikeman, shifting at lower RPMs results in greater fuel economy. I can personally attest to this. My Mazda has two driving modes, full auto and semi auto. In full auto it works just like any other automatic. In semi-auto, the car doesn't shift itself. This is like a manual but without the clutch, meaning you MUST shift it, it will not up-shift for you. If I leave the car in full auto it gets 33 MPG highway. If I go semi auto and keep shifts below 2500 RPM, I get ~36 MPG highway. If I drive as I normally do, which is upshift from 1st to 2nd at 5200 RPM, 2nd to 3rd at 5000 RPM and 3rd to 4th at 4500 RPM, I get a pathetic 27 MPG highway. A true manual transmission would yeild the same result.

So are automatics pre-set as to when they shift for you and non-adjustable? If so, they are stuck with whatever is factory set? Does driving manner affect the gas mileage on automatics?

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Yes Bikeman, shifting at lower RPMs results in greater fuel economy. I can personally attest to this. My Mazda has two driving modes, full auto and semi auto. In full auto it works just like any other automatic. In semi-auto, the car doesn't shift itself. This is like a manual but without the clutch, meaning you MUST shift it, it will not up-shift for you. If I leave the car in full auto it gets 33 MPG highway. If I go semi auto and keep shifts below 2500 RPM, I get ~36 MPG highway. If I drive as I normally do, which is upshift from 1st to 2nd at 5200 RPM, 2nd to 3rd at 5000 RPM and 3rd to 4th at 4500 RPM, I get a pathetic 27 MPG highway. A true manual transmission would yeild the same result.

So are automatics pre-set as to when they shift for you and non-adjustable? If so, they are stuck with whatever is factory set? Does driving manner affect the gas mileage on automatics?

 

Some automatics have shift points set by the factory, and these can't be easily changed. Others are electronically controlled and can vary shift points depending on driving style at any instant. This is called "fuzzy logic". Driving manner does affect gas mileage on automatics as well. If you accelerate harder, the car upshifts at higher RPM, and thus you get worse gas mileage.

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Yes Bikeman, shifting at lower RPMs results in greater fuel economy. I can personally attest to this. My Mazda has two driving modes, full auto and semi auto. In full auto it works just like any other automatic. In semi-auto, the car doesn't shift itself. This is like a manual but without the clutch, meaning you MUST shift it, it will not up-shift for you. If I leave the car in full auto it gets 33 MPG highway. If I go semi auto and keep shifts below 2500 RPM, I get ~36 MPG highway. If I drive as I normally do, which is upshift from 1st to 2nd at 5200 RPM, 2nd to 3rd at 5000 RPM and 3rd to 4th at 4500 RPM, I get a pathetic 27 MPG highway. A true manual transmission would yeild the same result.

So are automatics pre-set as to when they shift for you and non-adjustable? If so, they are stuck with whatever is factory set? Does driving manner affect the gas mileage on automatics?

 

Some automatics have shift points set by the factory, and these can't be easily changed. Others are electronically controlled and can vary shift points depending on driving style at any instant. This is called "fuzzy logic". Driving manner does affect gas mileage on automatics as well. If you accelerate harder, the car upshifts at higher RPM, and thus you get worse gas mileage.

My car must be "fuzzy" because sometimes I baby it and drive conservatively, while at other times I drive very aggressively. It is probably unsure of my driving style and therefore "fuzzy".

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I use 89 octane in my 01 Corolla LE automatic most of the time, but every now and then I'll fill up with 87 - I get better MPG with the 89 - I get 32 MPG with the 89, only 30 MPG with 87...sometimes even less, like 28 or 29 MPG.

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I use 89 octane in my 01 Corolla LE automatic most of the time, but every now and then I'll fill up with 87 - I get better MPG with the 89 - I get 32 MPG with the 89, only 30 MPG with 87...sometimes even less, like 28 or 29 MPG.

 

How many miles on that '01? I have an '02 with 133K and get about 30 MPG on the average. When I first bought the car, I was getting about 36 mpg and cannot seem to better it no matter what I do. I also notice I get better MPG with higher octane. I can't complain, it's paid for.

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I use 89 octane in my 01 Corolla LE automatic most of the time, but every now and then I'll fill up with 87 - I get better MPG with the 89 - I get 32 MPG with the 89, only 30 MPG with 87...sometimes even less, like 28 or 29 MPG.

 

How many miles on that '01? I have an '02 with 133K and get about 30 MPG on the average. When I first bought the car, I was getting about 36 mpg and cannot seem to better it no matter what I do. I also notice I get better MPG with higher octane. I can't complain, it's paid for.

My cars are all paid for. I would try a higher octane to see if I get better mileage results, but I don't think it's worth the extra cost. I go thru a tank of gas every three or four days, driving over 100 miles a day. Every fourth day I am at the gas station filling up.

Edited by Bikeman982

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ive said it before and i'll say it again, run the octane that your engine needs. otherwise you're increasing the likely hood of excessive carbon buildup in the chambers, exhaust ports, and the egr valve.

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