Hybrid Car – More Fun with Less Gas

How does the Prius hold up? - Page 3

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Posted by Tomes on April 22, 2008, 3:18 am

Well, see, that's the thing.  With the bladder in the gas tank checking the
MPG via fill-up is unreliable unless one checks over 30 tankfuls or so, with
each tankful increasing the potential accuracy of the measurement.  I am
going by the computer on my data above, it is all I have really.

Posted by bob on April 24, 2008, 2:16 am

that bladder is grossly off frequently, isn't it. at least that's what i
found so far.


Posted by Elmo P. Shagnasty on April 22, 2008, 10:23 am

How do you know that?

You can't, not at all, unless you measured the gasoline very carefully
and over a long period of time.  The gas tank design doesn't let you
accurately measure gas mileage by measuring your fillup and calculating
that against the odometer.

The only way to know, really, would be to start with a full tank on a
certain day of the year, say in June, then go a year and fill up the
tank again at the same pump on the same day in June the following year.  
Measure your miles driven in that year and calculate against the total
amount of gas you put in during the year.

The gas tank bladder simply doesn't allow a tank by tank measurement of
fuel mileage.

Posted by David Kelly on April 22, 2008, 1:44 pm
 Elmo P. Shagnasty wrote:

I have a logbook of the past 13,000 miles of fuel purchases and the
computer display which I manually reset with each fuel purchase.

The computer display runs about 5% optimistic.

Bladder, bladder, blah, blah. I get pretty consistent fills. Sometimes a
46 MPG measured for that tank, sometimes a 56, usually 52 to 54 when 56
is showing on the display. Its not really much different than my 2001
Sonoma which "got" 27.5 MPG the last tank. I don't really believe it as
I'm out of practice filling the truck having not bought gas since
January. 25 MPG would have been reasonable.

Posted by aol@aol.com on April 22, 2008, 6:52 pm
 Remove any excess weight.
Drive about 45 mph on a long trip.
Coast to red lights.
Have tires inflated to about 40psi.

You should see numbers above 55 MPG.

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