I figured it was a marketing gimmick to get you to buy 88 and then they would finally raise the price, but it’s been years. are they adding extra ethanol or something?

  • Hurculina Drubman@lemm.eeOP
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    4 months ago

    okay so I had AI do the math for me.

    the 88 octane fuel with 15% ethanol would need to be approximately 4.7% cheaper than the 87 octane fuel with 10% ethanol to compensate for the lower fuel efficiency caused by the higher ethanol content.

        • FiskFisk33@startrek.website
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          4 months ago

          E10 has an energy density of 108,608 BTU/gal and E15 has an energy density of 106,814 BTU/gal.

          source: http://www.airimprovement.com/reports/national-e15-analysis-final.pdf

          This gives us tha the 88 octane has 106.8/108.6 ≈ 0.983 times the energy density of the 87.

          1-0.983 = 0.017

          The correct number is that the 88 needs to be 1.7% cheaper than 87 to give equivalent distance per dollar.

          LLMs are fantastic tech, good at many things. Math is not one of those things.

          • Hurculina Drubman@lemm.eeOP
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            4 months ago

            yeah that’s why I labeled it as ai. like I can figure it out as a word problem to tell somebody, but I can’t figure out the math from there

            I didn’t feed it the energy density of e10 vs. e15, I just told it that ethanol was 30% less efficient, and gave it the percentages.

            • TheGalacticVoid@lemm.ee
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              4 months ago

              The AI does nothing with the percentages because it is an LLM, not an AI designed for math. All an LLM does is take a small number of words and turn them into a different set of words. It does not use your small set of words to run any formulas on your behalf.

    • invertedspear@lemm.ee
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      4 months ago

      Years ago I had an E85 compatible vehicle when that was how we were going to save the planet before hybrids came along. E85 was cheaper than unleaded, but after crunching the numbers it was always the exact same cost per mile. Considering there were almost no stations with E85 fuel available, it just never made sense to go far out of my way to pay the same.