2nd tank 57 mpg,

eaparicio · 09-25-2006, 06:59 PM

I filled up for the second time today and the average mpg on the display was 56.2 for 374 miles driven

I pumped 7.9 gallons in to fill the tank. The actual mpg compted is 47.3 which is an 8.9 difference. There was an 9.0 difference on the first tank. Is this normal? Which is probably the most accurate?

I am estatic with the mpg I have been able to achieve so far. If this keeps up I just might be able to reach 60 on this tank. I actually think the city portions of my daily commute help to bring my mpg up a little.

Ellen

eagle33199 · 09-28-2006, 10:37 AM

You'll need to gather a few more "data points" before you can really say... most people see up to a 2-3 MPG difference between the computer and calculated. With the car being so new, it's possible that the bladder is stretching out a little with each pump, meaning you're putting more gas into the car than you actually used. Give it a good 5-10 tanks and look at the average difference after that, see if the number starts going down.

If it continues to be such a large difference, try filling up at a different station for a few times... it's possible that the pump you're using is misscalibrated, rading slightly higher than whats actually going in... but it really is too early to tell, given the inaccuracies of the bladder.

Tempus · 09-28-2006, 11:04 AM

Averaged over 40K miles of record keeping (yes, it's a weighted average), my MFD reads 1.7 MPG higher than actual.

However, on a tank to tank basis the difference can be huge because the fillups are so variable.

San_Carlos_Jeff · 09-28-2006, 12:56 PM

<div class='quotetop'>QUOTE(Tempus @ Sep 28 2006, 08:04 AM) [snapback]325031[/snapback]</div>

Quote:

Averaged over 40K miles of record keeping (yes, it's a weighted average), my MFD reads 1.7 MPG higher than actual.

However, on a tank to tank basis the difference can be huge because the fillups are so variable. [/b]

Over the first 16k miles I'm in the same ballpark. My MFD reads 1.1mpg (or 2.4%) higher than actual.

tripp · 09-28-2006, 01:08 PM

Also note that outside air temp can really play Old Harry with your calculations on a tank by tank basis. If you live somewhere with large temp swings you'll find that your calcs are wildly off because the bladder has become more elastic or less so since your last fill up. Like other folks have said, over the long haul these sorts of variations should average out.

eaparicio · 09-28-2006, 10:30 PM

Thanks for the replys everyone. The bladder is something so new to me that I can see it is going to take me a little while to understand how it changes. I am used to the fuel tank holding what it is stated to hold. The temps. in DE can vary widely from early morning to late afternoon and from day to day. I am keeping track of my milage so I will see what the averages are over the next few tanks. I just hit 1000 miles on the odometer today. My MPG is sitting at 54.2 so I am a happy camper.

Ellen

09-28-2006, 10:37 AM	#2
eagle33199 Platinum Member Join Date: Mar 2006 Location: Minnesota Posts: 3,724 My Car: 2006 Prius Package: #7 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	You'll need to gather a few more "data points" before you can really say... most people see up to a 2-3 MPG difference between the computer and calculated. With the car being so new, it's possible that the bladder is stretching out a little with each pump, meaning you're putting more gas into the car than you actually used. Give it a good 5-10 tanks and look at the average difference after that, see if the number starts going down. If it continues to be such a large difference, try filling up at a different station for a few times... it's possible that the pump you're using is misscalibrated, rading slightly higher than whats actually going in... but it really is too early to tell, given the inaccuracies of the bladder. __________________

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09-25-2006, 06:59 PM	#1
eaparicio Join Date: Sep 2006 Posts: 21 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	I filled up for the second time today and the average mpg on the display was 56.2 for 374 miles driven I pumped 7.9 gallons in to fill the tank. The actual mpg compted is 47.3 which is an 8.9 difference. There was an 9.0 difference on the first tank. Is this normal? Which is probably the most accurate? I am estatic with the mpg I have been able to achieve so far. If this keeps up I just might be able to reach 60 on this tank. I actually think the city portions of my daily commute help to bring my mpg up a little. Ellen

09-28-2006, 11:04 AM	#3
Tempus Senior Member Join Date: Feb 2004 Location: Washington DC Posts: 1,693 My Car: 2004 Prius Package: #9 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Averaged over 40K miles of record keeping (yes, it's a weighted average), my MFD reads 1.7 MPG higher than actual. However, on a tank to tank basis the difference can be huge because the fillups are so variable.

09-28-2006, 01:08 PM	#5
tripp Which it's a 'ybrid, ain't it? Join Date: Oct 2005 Location: Denver, CO Posts: 3,900 My Car: 2005 Prius Package: #3 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 4	Also note that outside air temp can really play Old Harry with your calculations on a tank by tank basis. If you live somewhere with large temp swings you'll find that your calcs are wildly off because the bladder has become more elastic or less so since your last fill up. Like other folks have said, over the long haul these sorts of variations should average out.

09-28-2006, 10:30 PM	#6
eaparicio Join Date: Sep 2006 Posts: 21 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Thanks for the replys everyone. The bladder is something so new to me that I can see it is going to take me a little while to understand how it changes. I am used to the fuel tank holding what it is stated to hold. The temps. in DE can vary widely from early morning to late afternoon and from day to day. I am keeping track of my milage so I will see what the averages are over the next few tanks. I just hit 1000 miles on the odometer today. My MPG is sitting at 54.2 so I am a happy camper. Ellen