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toyota81

How Good Is Your Corolla On Gas?

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E85 is rated at 105 octane, but I don't see why cars would get less fuel economy with it then 87 pump.

It's rated at 105 Octane because Ethanol acts as a stabilizer to prevent the fuel form igniting too soon. That is the purpose of higher octane, to allow higher compression ratios, more aggressive piston and combustion chamber desing and further igniton advancing without causing knocking. Ethanol however has less energy content per unit volume. Basically the molecule has fewer hydrogen bonds ot break within the same amount of space. An alcohol also brings along oxygen to the the big molecular party which allows it to burn cleaner. If you run a car on 100% ethanol, you usually need larger injectors.

 

Also, with higher octane fuels, if a cars engine computer is unable to advance the spark to compensate for the higher octane, it will produce less power because the ingition will occur too long after reaching top dead center on the pistion stroke.

 

Remember Octane is not a rating of the energy content, but rather the resistance fo the fuel to pre-ignition. The fact however that it's more stable allow you ot use more aggresive igniton timeing, this can allow you to make more pwoer. But the fuel by itself does not do this.

 

Octane rating is not the same as "proof" or alcohol percentage on liquor. I think this is how most people try to rationalize the numbering system. The difference is that wiht liquor, the second compound if water. With gasoline, the other compounds are also hydrocarbon and contain the same energy content per volume.

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trap

I know exacly what a octane rating is for. I just don't buy that E85 is really 105. I have software that logs my ECU data for my turbo car and I have to turn down the boost when I use city gas (with 10% ethenol). If I can get 93 octane without ethenol, then my car will run better. I can turn up the boost a little without the knock sensor going off and timming advances to the full amount. I look forward to Indiana gas again.

 

As far as the cars ECU not being able to advance the spark enough, that is stupid. Either e85 doesn't have 105 octane, or car makers are the biggest tease ever. They can program a ECU for e85 and if the car can run on it, then it should be able to take advantage of it. E85 as it is today is just to make people feel better about running clean fuel. Cars get horrible gas milage and even tho the fuel might be cleaner, you gotta fill up way more often when using it. Some cars used to have a fuel swtich to choose the type of fuel you were running. Fords turbo thunderbird and theSCed MR2 both had a regular unleaded setting and a preimium fuel setting. There is absolutly no reason that all e58 cars shouldn't have this. Even the Dodge SRT4 has a switch box upgrade with a ECU flash that lets the driver take advantage of 100 octane street fuel.

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A lean fuel mixture is differnt than predetonation from lower octane, but can have similar symptoms. It's possible that the ECU in your older MR2 is unable to detact and compensate for 10% ethanol. It might be beyond it's range of adjustemnt. Although if it was, I'd expect the CEL to come on.

 

I guess it just depends on hte engine. My carbeurated 900cc motorcycle is far less picky about what fuel I use. I can't tell much difference when I run 89 or 90 octane wiht 10% ethanol vs. running 93 octane wiht no Ethanol. On hte other hand my previous 600cc fuel injected motorcycle (closd loop with no O2 sensor) was a little more picky. You could run regular octane and 10% ehtanol as the manual stated, but it definitely ran a little smoother with higher octane. Although it also depended on the temperature nad humidity outside despite have a EAT sensro.

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Fords turbo thunderbird and theSCed MR2 both had a regular unleaded setting and a preimium fuel setting.

a friend had a supercharged tbird but I cant remember if he had that fuel switch but I would assume so. my sc mr2 on premium setting with a small amount of alcohol would run great thats all I know.

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A lean fuel mixture is differnt than predetonation from lower octane, but can have similar symptoms. It's possible that the ECU in your older MR2 is unable to detact and compensate for 10% ethanol. It might be beyond it's range of adjustemnt. Although if it was, I'd expect the CEL to come on.

 

I guess it just depends on hte engine. My carbeurated 900cc motorcycle is far less picky about what fuel I use. I can't tell much difference when I run 89 or 90 octane wiht 10% ethanol vs. running 93 octane wiht no Ethanol. On hte other hand my previous 600cc fuel injected motorcycle (closd loop with no O2 sensor) was a little more picky. You could run regular octane and 10% ehtanol as the manual stated, but it definitely ran a little smoother with higher octane. Although it also depended on the temperature nad humidity outside despite have a EAT sensro.

I don't have a MR2, I been in one that had the regular/premium fuel switch.

 

I have a turbo Mitsubishi. It's not a lean condition because I have a ajustable fuel pressure regulator. I've tried 1-2psi above the stock level with no luck. At that point, it just rises 1:1 for every psi of boost. It's a mechanical FPR and so was the stock one both doing the same thing, only I needed a aftermarket one cause my fuel pump was over running the stock FPR.

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Yay!

 

Went 376.5 miles on 10.417 gallons of gas.

Cost me $34.37 to fill up which was less than my fuel economy of ~36.14 MPG.

 

Lol . . .

 

This tank lasted me from 08/22/05 to 09/18/05 or 27 days.

My 1993 Geo Prizm LSi 5 SPD Manual is rated at 28/35 and I got ~3% higher than what it is rated.

 

Not bad for a 12 year old car.

 

:)

 

So my fuel economy was:

 

US: ~36.1 MPG

UK Imperial: ~43.4 MPG

Metric System: ~6.5 litres per 100 Km

Edited by Louisville Slugger

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I don't know if I believe it or not, but Mythbusters did a test on whether air conditioning hurts your gas mileage. Apparently its the same...at least on the track they did it on, but gas mileage was worse with the windows down.

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Guest dlichterman

I got about 26 MPG on my last test.....but thats:

 

A 25-40 Minute commute, depending on traffic. When it is bad, its stop and go for a good few miles on the freeway and lots of red lights.

 

This is a 21 mile round trip, with about half and half freeway to city

 

I forgot my calculator, and FLEW home and back one day in my psycho-racing mode, which probably killed my gas milage

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I don't know if I believe it or not, but Mythbusters did a test on whether air conditioning hurts your gas mileage. Apparently its the same...at least on the track they did it on, but gas mileage was worse with the windows down.

They also used a Ford Explorer, which because of it's size and lack of aerodynamics, I would not expect there ot be a big defference. It will get poor mileage no matter what. They also didn't do a true controlled test. THye should have switched vehicles and run the some twest a second time then averaged the results.

 

On a smaller car like a Corolla, Camry, Civic or Accord, I'd exect there to be a 1-2 mpg difference.

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One thing people forget is that you need ot average at least 3 fill-ups together. Why? because of fill level error. I found this out last weekend. On my '04 Accord Coupe (4 cylinder auto) I achieved 40mpg by traveling 480miles on 12 gallons of gas in 100% freeway conditions. I was shocked. I knew I had a light tail wind, but this car shouldn't be capable of this kind of mileage in any condition. I was crusing 70-75mph and even went 80mph for a long stretch in Michigan (just to keep up with traffic, they drive fast there)

 

How could this happen?... anyone? anyone? Here's how...

 

On the first fill up, the tank topped off high by 1/4 gallon or more. On the next fill-up, the tank topped off low (by twice the previous amount), making it appear that again, I used less gas. On the 3rd fill-up that weekend, I achieved 32mpg which was a little low for 90% freeway driving.

 

I learned that you need ot average several tanks together because not every nozzle at each gas station behaves the same way. I alos learned that thsi Accord gets pretty good mileage and because of excellent aerodynamics and tall gearing, isn't affected by driivng faster. 80mph (2500RPM) gets only slightly less mileage than 65mph (2200RPM).

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labor day weekend trip to Niagara Falls, I consistent got 40 mpg for 3 tanks on my 95 DX. I drove between 65-75 mph - mostly around 70. New York sure has a lot of troopers - i counted 10 each way on my 500mile trip.

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My '98 VE automatic's best was 37.7 mpg (mostly hwy + a little city) but my dad's '02 LE automatic recently got 43 mpg (mostly hwy + a little city). I couldn't believe it--11 miles in Austin traffic and then 159 miles from local roads in North Austin, through 71 freeway, through I-10 freeway, and finally to my parents' house on local roads in Southwest Houston. I used the AC for a short stretch only. It's previous best was also 37.7 mpg, coincidentally.

 

I measured my '98's city to be something awful like 22 mpg, but I figured that's due to the long stop lights and other unavoidable delays in the particular area where I was driving. I'd like to think other comparable non-Toyota cars would also do as poorly under the same conditions. :)

Edited by tracey

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Guest dlichterman

my 98 gets bad city mileage too....i just wish I had more open freeway too.....when we say freeway now there is stop and go freeway.........stupid designers...

 

but im going to put some seafoam in my gas and see what happens

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It is important that you have to fill up at the same pump every time, that way the machinery clicks off is the same, the way the pipe fits in the tank is the same, the slope and angle the car and tank sits is the same, etc etc etc.

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I did a quick 1 day trip wednesday to sign for a lot that I bought in the village where my parents and ancestors come from. To and from on the same tankful;

 

828 km (515 miles) and 46.4 liters of gas. Same gas station as previous day fillup and same pump. Did 104 km with the low fuel light on...

 

5.6 liters/100 km = 42.0 mi/USG = 50.4 mi/ImpG.

 

Conditions were perfect; 99% highway, tail wind all the way to my destination, lots of cruise control at 65-70 mph and a fair amount of construction zones and urban areas in 5th at 50-60 mph. Temperature was between 14 and 23C. No AC.

 

Actually, I'm a bit disappointed by those numbers as I didn't equal or beat the highway numbers for my car, which I did a number of times with the Toyota and 2 Hondas I've owned in the past.

 

Larger and grippier tires than stock (Yokohama Avid TRZ 195/65-15) with "only"

29 PSI front and 27 back might have played a role here and I'm running Esso XD-3 full synthetic 0W-30 oil that doesn't carry the Energy Conserving label. Also, the car only has 7500 km. Break-in may not be 100% completed.

 

As for the tires, I like their smoothness, comfort and bump absorption just like they are now and unless I had to carry a full load, prefer to pay a small penalty at the pump.

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