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Old 08-28-2014, 04:08 AM   #4 (permalink)
2000mc
herp derp Apprentice
 
Join Date: Oct 2008
Location: Lawrence, KS
Posts: 1,049

Saturn-sold - '99 saturn sc1
Team Saturn
90 day: 28.28 mpg (US)

Yukon - '03 GMC Yukon Denali
90 day: 13.74 mpg (US)
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Quote:
Originally Posted by niky View Post
If the mileage is creeping up steadily, then you have to figure out why and get the car stable enough to have consistent results. Could be the car running in on the oil... or temperatures becoming more ideal as the day gets warmer/cooler or as air pressure changes.

How do runs 3 and 4 compare? How do runs 6 and 7 compare?
1 43.25
2 43.4
3 41.7
4 42.7
5 42.75
6 43.3
7 43.75
8 43.15
9 44.4

The individual east west runs have even greater variations, it is surprising how when all the runs without the skirts are averaged out, how close it is to the average of the runs with skirts. Which i guess is why I used 9 runs instead of 3.

I think the mileage keeps going up with trans, engine oil, tire temps, and maybe increased rake as the fuel tank gets lighter. I had thought before that it stabilized after about half an hr, but had since found it only slowed, and haven't found the point where it stops going up. I chose a test area on the far side of town to help warm things up, and I'm guessing by the end of the last run I put over 80 miles on the car since I left home, and the mileage still climbing.

The car burns oil at about a qt/1500mi which I wouldn't think would have any significant affect. Temps/ weather were basically stable throughout the test, which I don't really think was a factor as I would have been more surprised to not see this happening again.

Anyone have other examples of longer tests showing mileage creep, or totally stable for that matter?
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