Randy - Calculated MPG vrs Actual and Mobil 1 - 26HP gain from oil change
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Randy - Calculated MPG vrs Actual and Mobil 1 - 26HP gain from oil change
Flicking though old posts today and I was reminded of a post earlier this year regarding Mobile 1 and a 26HP increase.
Giving some thought to the computers calculation of MPG. My understanding is that this calculation is based on a ideal model calculation made by the computer whcih until now I assumed would be accurate...
If it is accurate then Randy's calculation of a 26HP gain from Mobil 1 looks good.
<a href="https://forums.audiworld.com/a8/msgs/75960.phtml">Did I just gain 26 HP from a oil change</a>
I recenty saw on TV of all places a test where the computers MPG was taken over a constant speed on a race track over 15 LAPS. A set amount of fuel was put in the tank and the car driven at a constant speed on the track until it ran out of gas.
The puspose of this test was to determin if fuel economey was effected by A/C more or less than the windows being down. I had a problem with the conclusions since I feel this is going to be most effected by speed - higer the speed the more effect of having the windows down.
Anyway back to the point, dispite the conclusion, it showed that the calculation made by the computer was signiff****ly off from actual. This being the case, I think I may have found a hole in Randy's calculation.
Any merit to this train of thought?
Giving some thought to the computers calculation of MPG. My understanding is that this calculation is based on a ideal model calculation made by the computer whcih until now I assumed would be accurate...
If it is accurate then Randy's calculation of a 26HP gain from Mobil 1 looks good.
<a href="https://forums.audiworld.com/a8/msgs/75960.phtml">Did I just gain 26 HP from a oil change</a>
I recenty saw on TV of all places a test where the computers MPG was taken over a constant speed on a race track over 15 LAPS. A set amount of fuel was put in the tank and the car driven at a constant speed on the track until it ran out of gas.
The puspose of this test was to determin if fuel economey was effected by A/C more or less than the windows being down. I had a problem with the conclusions since I feel this is going to be most effected by speed - higer the speed the more effect of having the windows down.
Anyway back to the point, dispite the conclusion, it showed that the calculation made by the computer was signiff****ly off from actual. This being the case, I think I may have found a hole in Randy's calculation.
Any merit to this train of thought?
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Calculated versus computer MPG
For whatever reason, every time I "manually" check my mpg with fuel added and odometer, the results agree very well with the computer mpg average. I have a high level of confidence in that 1.4 mpg difference reported in my earlier post, especially when the high was the best I'd ever seen.
Actually, I've almost come to the conclusion that the computer is more accurate. It doesn't seem to be sensitive to whether or not I try to fill the tank with that last drop, filling all the way to the top of the fill pipe neck. Since I assume the computer is making a calculation based on the odometer and a fuel flow that's somehow metered/measured, the results are not sensitive to a fuel tank level above maximum.
Where my computer is wildly incorrect, though, is when calculating "miles to empty". After refueling, the computer often reports 550+ miles to go, and it doesn't seem to lose it's optimism until the tank is about 1/3 down. From that point on, the "miles to empty" estimate is very accurate.
BTW: What speed did they run those 15 laps, and what was their AC versus windows conclusion?
Actually, I've almost come to the conclusion that the computer is more accurate. It doesn't seem to be sensitive to whether or not I try to fill the tank with that last drop, filling all the way to the top of the fill pipe neck. Since I assume the computer is making a calculation based on the odometer and a fuel flow that's somehow metered/measured, the results are not sensitive to a fuel tank level above maximum.
Where my computer is wildly incorrect, though, is when calculating "miles to empty". After refueling, the computer often reports 550+ miles to go, and it doesn't seem to lose it's optimism until the tank is about 1/3 down. From that point on, the "miles to empty" estimate is very accurate.
BTW: What speed did they run those 15 laps, and what was their AC versus windows conclusion?
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MPG was calculated at 70MPH and A/C vrs Windows at 45MPH
Here is a summary cut from a post on the net:
The results were mixed.
First they connected a computer to the disgnostic connection of a Suv.
The computer measured the air consumed by the engine and computed the fuel mileage while the Suv traveled around a test track.
Test 1
With a/c on- 11.7 mpg.
Without a/c and windows open-11.3 mpg.
Test 2
The boyz emptied the tanks of 2 "identical" Suvs, then filled them with exactly 5 galllons of gas, and then drove around a test track at 45 mph until the first one ran out of gas.
The Suv using the a/c ran out of gas first.
The Suv with the windows open ran for another 15 miles before quitting.
Make your own conclusion, but consider that they had to manually empty the tank by pumping the gas out before they added the 5 gallons of gas.
The results were mixed.
First they connected a computer to the disgnostic connection of a Suv.
The computer measured the air consumed by the engine and computed the fuel mileage while the Suv traveled around a test track.
Test 1
With a/c on- 11.7 mpg.
Without a/c and windows open-11.3 mpg.
Test 2
The boyz emptied the tanks of 2 "identical" Suvs, then filled them with exactly 5 galllons of gas, and then drove around a test track at 45 mph until the first one ran out of gas.
The Suv using the a/c ran out of gas first.
The Suv with the windows open ran for another 15 miles before quitting.
Make your own conclusion, but consider that they had to manually empty the tank by pumping the gas out before they added the 5 gallons of gas.
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Re: Calculated versus computer MPG
I am quite surprised about the first part of your observation, as the readings on the average MPG I see are consistently overly optimistic, to the tune of 10% or more. I commute 80 miles roundtrip, 72 of which are HWY miles. The readout for average between fill-ups shows 25+ MPG, but a quick back of the envelope calculation gets me 22 MPG at the most. Hence my surprise about your comment. I'd be interested to hear from others about their observation - mybe its just my car that is the aberration?
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In city I have 14 MPG, but.....
On our summer vacation to the Yellowstone park my average was 22.7 MPG and I wasn't driving always under the speed limit. ( two tickets ). After refueling on the highway, sometimes it showed 600-700 miles to empty, even 900 downhill with engine brake. The city driving is killing the MPG, not the high speed. Check out my previous car's MPG at high speed.
<img src="http://pictureposter.audiworld.com/80919/vw_gti_vr6.jpg">
<img src="http://pictureposter.audiworld.com/80919/vw_gti_vr6.jpg">
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Ditto- owned both...
... and my A8 did much better in the MPG department- as high as 29 mpg at a constant 70mph.
FYI, just drove back in my '01 S8 to Des Moines (from Minneapolis). In northern Iowa, where it is straight and flat, i ran 72mph for a 1/2 hour and averaged 22.9 (with wife, child, and full trunk.
I'm Running Mobil 5w-30. I'd love to think Mobil 1 0w-30 R would give me those kind of improvements.
Will this oil void out our factory warranty?
FYI, just drove back in my '01 S8 to Des Moines (from Minneapolis). In northern Iowa, where it is straight and flat, i ran 72mph for a 1/2 hour and averaged 22.9 (with wife, child, and full trunk.
I'm Running Mobil 5w-30. I'd love to think Mobil 1 0w-30 R would give me those kind of improvements.
Will this oil void out our factory warranty?
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Can't see anyway it could void the warrenty
Some older engines had issues with some of these fully syns slipping past the rings due to worn or sloppy tolarences.
I'm just waiting for the 5K mark to come along, and then in goes Mobil 1 0w-30.
I'm just waiting for the 5K mark to come along, and then in goes Mobil 1 0w-30.