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Most often I run the cars to the rolling roads and have them optimised. money is a little tighter just now.so, where do I try fettling to raise the mpg on both my aeros to above 22.3! :roll: Its not my driving style as my dad is getting the same out of the 2nd car and hes a very light foot and all the time in the world :cheesy:

Any thoughts and help sincerely appreciated. :D
 

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Are your tires properly inflated? Check those at least once a month

Are you running premium fuel? 87 Octane will result in lower fuel economy by up to 20% from my experience. (compared to 93)

Are your spark plugs gapped correctly? Check those, consider new ones if they are more than 15,000 miles old. (make sure you get the right ones, do a forum search and you'll find a post about them)

Are you running your airconditioner?
AUTO = A/C activated
ECON = A/C compressor always off
This can make a huge difference in gas mileage. I never run auto unless my windows are foggy or if its over 80 degrees outside.

Look into some seafoam treatment, search seafoam and you'll find some good posts.

Winter will kill gas mileage also. In the summer i average 29.5 Mixed highway and city. In the winter i average only 24.5
 

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boon94 said:
Are you running premium fuel? 87 Octane will result in lower fuel economy by up to 20% from my experience. (compared to 93)
Actually, running the lower octane fuel results in better gas mileage with the saabs. With the knock sensor within the engine, if the car detects knock, it will adjust so the knock is eliminated. With the way the car is designed, the lower the octane, the better the mpg. The higher the octane, the better the performance.
 

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justin.graeff said:
Actually, running the lower octane fuel results in better gas mileage with the saabs. With the knock sensor within the engine, if the car detects knock, it will adjust so the knock is eliminated. With the way the car is designed, the lower the octane, the better the mpg. The higher the octane, the better the performance.
Thought I've noticed this from my own experience with the newer higher octane fuels. Have you got anything to backup your facts though? i'm interested in more details about this. I only get 370km on a full tank on average at the moment. I used to get close to 600km sometimes but that would mostly be because of the modifications I've done.
 

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justin.graeff said:
Actually, running the lower octane fuel results in better gas mileage with the saabs. With the knock sensor within the engine, if the car detects knock, it will adjust so the knock is eliminated. With the way the car is designed, the lower the octane, the better the mpg. The higher the octane, the better the performance.

I ALWAYS get at least an extra 50 miles per tank on 93 compared to 87, and have tested this many many times.

Our cars are designed to run on high octane, and only turn into compatibility mode when running on low octane. IE poor performance, horrible turbo lag.

If you look in old manuals, the 9000 turbo recomends at least 91, but if it isnt availible can run on 87. The AERO requires 93.

the OG9-3 (turbo) manuals explicitly state that running less than 91 octane will result in reduced performance, IE takes more gas to do what you want to do.

In a regular car, running a higher octane will cause no advantage, our cars are designed for high octane gas
 

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I'd have to agree with Justin. I always get better mileage on lower octane. perhaps because there is more boost to be accessed. Whatever the cause, I get better mileage on lower octane.
 

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It's important to remember that octane ratings are expressed differently around the world:

[edit] Measurement methods

The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel in a test engine with a variable compression ratio under controlled conditions, and comparing these results with those for mixtures of isooctane and n-heptane.

There is another type of octane rating, called Motor Octane Number (MON) or the aviation lean octane rating, which is a better measure of how the fuel behaves when under load. MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, a higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern gasoline will be about 8 to 10 points lower than the RON. Normally fuel specifications require both a minimum RON and a minimum MON.

In most countries (including all of Europe and Australia) the "headline" octane that would be shown on the pump is the RON, but in the United States, Canada and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. Because of the 8 to 10 point difference noted above, this means that the octane in the United States will be about 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the "regular" gasoline in the US and Canada, would be 91-92 in Europe. However most European pumps deliver 95 (RON) as "regular", equivalent to 90-91 US (R+M)/2, and even deliver 98 (RON) or 100 (RON).
-Wiki

Here in NZ we have 91,95 and 98 (100 is available in some places at the pump).

I have always found that the 95 offers best mileage.
 

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It all comes down to your right foot. Theoretically, lower octane should give better mpg because you will ultimately pump in less air(less boost) therefore computer will spray less gas. However, if you are a spirited driver like i am, then you will keep pressing the right foot down because the car won't give you perfomance you are used to. This will lead to more time in high load condition, which ultimately will reslt in less mpg. However, again, if you are a spirited driver, even if you put 93 in, you will probably still not get the best mpg.

I, after tuning, now in winter get bout 21mpg. In warmer times(when i don't warm up) I get more like 24. However, if I need to, and baby the accelerator pedal(about 90mh average), I can get about 500 miles out of a tank, on a highway(17 gallons), which is almost 30 mpg.

Klim
 

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just a thought here, but ill share it anyway. take 15 gallons of regular (87 here) and 15 gallons of premium (92 here). with premium, it should take less effort to burn, correct? so then with regular, it will take more effort to burn it. with that being said, you can use less of the higher octane to achieve the same result as the lower octane, resulting in there being more left from the original 15 gallons, meaning that the premium is getting better gas mileage... just a thought
 

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I see a lot of disagreement here!

I know a lot of you are saying that you'll get better gas mileage with the higher octane fuels. And, maybe on other cars you're right. BUT, with saabs, they designed the engines to perform better with higher octane; as they should, but they don't get better gas mileage. If you want better gas mileage while driving nicely, the lower octane is what you want. True, you'll suffer a performance loss, but you'll also gain extra miles on a tank.

Personally, I always use the premium 92 octane because it burns cleaner and is better for the turbo. I could care less about what kind of gas mileage I get, I want my engine running past 200k miles! I am now at 196k miles. I'm getting there!
 
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