Has anyone ever tried filling their thank to exactly the same gallons for several tanks in a row? Say maybe 8 gallons every time? Wouldn't that give a pretty darn accurate reading of MPGs? Maybe I'm just tired and that wouldn't make a difference though...
Wouldn't make a difference. The bladder makes it hard to determine that the "Add Fuel" warning comes on at the same fuel level every time. e.g. First time, we pump with 1 gal left. So that'll be 9 gallons in the full tank. Second time, it may come on at 3 gal. So you've used 6 gals and try and put in 8 gal. for a total of 11 gal. Third, maybe i'll come on at 3 again so there's 8 gal. used. etc etc
But how would we know there was 1 gallon or 3 gallons left? Wouldn't it be effective to fill at an intermediate point, say at 5 pips, and calculate from that point?
It would work only if you ran out each tank. If you started by running your tank dry, then adding a fixed amount, you could run it dry again and have a fair amount of precision. Not perfect, but fairly good. The reason that it wouldn't be perfect is that the exact point at which a tank runs dry varies. Going up a hill or around a corner will change the level at the pickup point. As for the suggestion in the OP, that doesn't work because you still have uncertainty. You don't know how much fuel was in the tank before you added a fixed amount, and you don't know how much is left when you go to add fuel again. The fuel gauges in cars are just not that accurate. The Prius gauge is no exception. Tom
8 gallons on a really cold day, wouldn't be the same as an indicated 8 gallons on a hot day, also there would be pump to pump variations. Anyway, who cares? Just fill it till the pump clicks off, and drive away happy .
Pat, assuming you were referring to my post, yes, I probably need a lot of beauty sleep; not a lot of beauty genes in my hillbilly background. But I was being serious in the post...can we get the same results by filling at a higher intermediate point as we can by going to a specific low pip or letting the tank run dry (not a happy thought, it seems to me).
No, I was refering to the OP. I really don't see the point. If you use 7 gallons a week but put in 8 gallons a week, what will happen? Just fill up, pay and drive off, it isn't rocket science.
