I just tried a tank of 87 for the first time. I averaged the same MPG according to the dash info (reset of course).
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have to do the math......gallons filled/ miles driven.......the trip computer is very inaccurate. Have seen it off by 1 gallon either way.
If I am doing a long road trip, when I know I am setting the cruise for 600+ miles.......i will have no problem using 87. zero need for extra power when doing 75mph for 5 hours straight.
Any other time, it is 93 for me.