Mileage Calculation #3 - Shell gasoline

It's only been a couple days since my last fill up. I've been riding a lot if you can call 1 gallon's worth, "a lot." Again, I filled up with regular 87 octane. I used Shell this time instead of Chevron. I'm not expecting a difference on the next calculation. Let's see what this time looks like.


(2691 - 2627)/0.966 = 66.26 mpg

What happened??? I thought my mileage was supposed to be 103! or at least something close to it! Grrrr....after checking my math on the last one, I found that I miscalculated big time! My mileage last time was only 78 mpg! Happy for a couple days for nothing. Sucks.

But even then, there's still a big discrepancy. I was getting 78 mpg before and now I'm getting just a bit over 66 mpg? That's a 15% difference! This is weird. I'll have to continue calculating my pennies for the next few fillups to see what's going on. My driving habits hasn't changed, so I wonder what could be going on. The next calculation should tell me a bit more.

UPDATE: I just realized something. Unlike a car, the scooter doesn't top off the gas by itself. The pump doesn't just stop letting you know the tank is full. So just b/c I put 0.966 gallons into the tank this time, doesn't mean that I used that much on the last tank. In fact, I know I didn't b/c I definitely topped it off more this time. Today was the first time I ever topped it off so that the fuel level was almost touching the inner bottom lip of the filler tube. So I guess these past two tests mean zilch. I'll have to start the tests over with a consistent full tank each time.