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Whats Your Average MPG?

Old 11-18-2011, 06:50 PM
  #26  
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Not slamming on anyone. You know what you get when you buy an RX-8. If you have to drive a 100 miles to work and are worried about mileage, buy a Prius. If you want thrills and smiles you do 16 MPG in an 8.

There's nothing worse than people who buy fun fast exciting cars and drive them like an old fart "saving gas" it's the dumbest thing ever.

So in conclusion. Accept the MPG or trade it in. That simple.
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Old 11-18-2011, 08:24 PM
  #27  
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Originally Posted by wrightcomputing View Post
Comparing MPG from UK to USA is not relative because the gallons are different sizes not sure the exact size but a UK gallon is just under 5 litres and a USA gallon is about 3.8.
Therefore 25 MPG in the UK is the same as 19 MPG in the UK.
Then the fuel is better Octane rate in the UK at 95 - 100 whereas the USA is 87 - 93.

The same car will get much better MPG in the UK than the USA because of better fuel and bigger gallons.

Actually in the UK it is measured by RON(research octane number) on the pump and in the US we have the AKI/PON(anti-knock index/Pump Octane Number, which is the average of RON & MON) number posted on the pumps. MON(motor octane number) is generally around 10-ish points lower than RON but I guess it can vary. The UK does seem to have a bit higher octane but not as high as the numbers would lead you to believe when comparing the two.

Another thing is this car calls for premium, which here is 91 or 93 aki depending where you live. Using anything above that in your car without a reason is not going to help you with anything unless you are going FI or have a reason to reduce possible detonation. The octane rating is only a measurement of the fuels anti-knock properties not the energy it contains or even the amount of octane in the fuel. It is a scale of 0 to 100, 100 being 100% iso-octane(stable fuel) and 0 being heptane(detonates easily) and yes there are fuels above a 100 octane rating but that is because that fuel is more stable or less susceptible to detonation than 100% iso-octane. So a gas rated at 90 octane has the same qualities as 90% iso-octane and 10% heptane.

Was hoping to keep that short but it just seemed everything I added needed another thing to explain it lol.
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Old 11-18-2011, 09:20 PM
  #28  
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Originally Posted by RIWWP View Post
The cost difference between my 8's mileage and my wife's car's mileage means that I get about 121 miles of fun for the same cost as my wife going to a movie (without going to concessions).

Or about 857 miles for about the same cost as a new pair of her shoes.


I think I'm getting a better bargain.
\


lol I love the comparison between car and wife, made me giggle abit, because it so true. Combined city and highway I get about 17.1, at least what my cobb told me when I had one. I think its funny when people complain about poor gas milelage on an rx8, 1 its a rotary it gulps fuel down, 2 its a sports car, gotta pay to play mang.
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Old 11-18-2011, 10:20 PM
  #29  
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21-22 hiway, when i'm in texas and can get 93 octane no alcohol, it jumps to 25-27. Go corn growers, another con by our government.
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Old 11-19-2011, 07:55 AM
  #30  
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After new plugs - coils - wires - fuel pump and fixing three intake vacuum leaks I get 19.x with around 50/50 city/highway, high RPM every chance I get.

I don't think it gets any better than this; what a great car!
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Old 11-19-2011, 08:18 AM
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I bought my '05 used and got 11mpg on the first fill up. But I thought it was because I was driving it like I stole it. 2nd tank I drove like a granny and it only improved slightly...

I replaced the plugs/coils/wires & started premixing. Gradually it's gone up to a steady 15.5mpg average. I still drive aggressive and its all city, always in stop & go traffic with about 25+ stop lights between home and any given destination. Sometimes I hate living in CA!

I still haven't taken an all highway trip with it yet, so I have no clue how it does on the highway.
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Old 11-19-2011, 02:19 PM
  #32  
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rotflmao,

Post 2, brilliant as it is, returns this thread as the top choice.

BTW, 22 mpg, mixed city, back roads and some highway, one carbon burn, 70 miles a day. My 6s did 25 mpg on the same loop.

Last edited by 04Green; 11-19-2011 at 02:22 PM.
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Old 11-20-2011, 12:02 AM
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I get around 19-20mpg in the winter and 22-24mpg in the summer time.
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Old 03-24-2019, 09:02 PM
  #34  
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Iíve owned my 8 for a few months now, and ive averaged as low as 9mpg and only been able to squeeze 11.25mpg driving normal for the most part and doing as much highway as possible. I calculated this by using the trip odometer and dividing by 16 (which is what I found to be gas tank capacity) because I donít have an accurate obd reader. So that mpg calculation doesent take into account for gas used in warm up time everytime I start my car so my question is has anyone calculated both ways to see the difference? Also how much gas do you fill up with when gas light is on? Last couple times Iíve noticed itís only about 13 gallons instead of the 16. Using that figure for calculation helps some but still significantly Lower than what Iíve seen most averages. For reference Iíve got new spark plugs coils coil wires cat delete a catback system and ecu has been reset a couple times. Premixed with about 8 oz 2 stroke oil at fill up. Thanks for any input
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Old 03-24-2019, 10:21 PM
  #35  
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Calculating fuel mileage is the easiest thing in the world. You note how many miles you drove and how much fuel you put in the tank when you fill it completely.
My information is in my signature.

13 gallons when the light comes on is right, that's what I usually see.
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Old 03-25-2019, 04:38 PM
  #36  
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Originally Posted by Masont72 View Post
Iíve owned my 8 for a few months now, and ive averaged as low as 9mpg and only been able to squeeze 11.25mpg driving normal for the most part and doing as much highway as possible. I calculated this by using the trip odometer and dividing by 16 (which is what I found to be gas tank capacity) because I donít have an accurate obd reader. So that mpg calculation doesent take into account for gas used in warm up time everytime I start my car so my question is has anyone calculated both ways to see the difference? Also how much gas do you fill up with when gas light is on? Last couple times Iíve noticed itís only about 13 gallons instead of the 16. Using that figure for calculation helps some but still significantly Lower than what Iíve seen most averages. For reference Iíve got new spark plugs coils coil wires cat delete a catback system and ecu has been reset a couple times. Premixed with about 8 oz 2 stroke oil at fill up. Thanks for any input
You don't normally run the tank dry, and running it dry can damage the (already fragile) fuel pump.

Use Fuelly if you don't want to do the math.

11 MPG is too low unless you are tracking for a good chunk of the tank. My spirited DD with 80+% of city driving usually returns 14 MPG.

Two things come to mind:

- Don't reset the ECU by disconnecting the battery needlessly. It needs to record STFT and LTFT to run the car optimally. Resetting the ECU erases these info.

- Unless you drive a carburated car, there is zero need to warm up the car. At best you are just wasting gas, at worst you can create some other problems. Start the car, wait 15 to 30 seconds, then just drive gently. This applies to any fuel-injected vehicle.
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