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Old 02-03-2023, 08:29 PM   #33 (permalink)
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spyder2 - '00 Toyota MR2 Spyder
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Originally Posted by hayden55 View Post
I don't seem to notice a difference over whats explained by thicker air resistance.
Hmmm now that I think of it, I was comparing mpg between what I thought were "basically the same" temperature (~60F vs 47F?) but the air density difference is actually a non-negligible 2% ish. So the car needs ~1% more power to move and the fuel has at least 2% less energy, so I'm only missing 4% (7% loss)...slightly colder transmission and engine oil might account for that but I have my doubts as the coolers all have thermostats built in and I blocked off much of the grille.

I'm too cheap to go fill the tank at a Shell just to see if cheap gasoline has lower density alkanes to make it cheaper, but it still feels like the gasoline is making more than a 2% difference to me.
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