Stupid question of the day number 2

bigbaldcuban · 09-03-2004, 03:23 PM

I've only filled up twice, but I notice that atthe beginning of my tank I'm getting 50/52 MPG. As the tank empties it slowly decreases and ends up about 45 MPG (I'm happy with 45). Is it just a matter of me driving smarter or is this just a normal occurence with the whole bladder/tank thing?

rflagg · 09-03-2004, 03:41 PM

Instantaneous MPG, or average MPG on the Consumption screen?

-m.

bruceha_2000 · 09-03-2004, 03:47 PM

How close to "the begining"? Nice warmed up car filled then driven at 35 on the flat will have better mpg than later in the tank when you have had a lot of cold starts, highway driving, etc

bigbaldcuban · 09-03-2004, 04:37 PM

This is on the avg. MPG screen. Both times I fill up it's in the mornings about 6:30. The cars running for about 2 minutes before I get to the Gas station

Marg · 09-03-2004, 04:58 PM

Hmmm, interesting. For us, filling with a warm tank yields good numbers at first getting worse over time. Filling with a cold tank yields poor numbers at first, getting gradually better.

However, no matter what the conditions are when filling the tank, we nearly always finish the tank at an average of 4.6 litres per 100 km. It's maddenly predictable.

daniel · 09-03-2004, 06:35 PM

I'm guessing it's because the car burns more gas during warm-up. You're filling after warm-up, so that first morning's drive gets better mileage. After that, it settles down to the real average.

Either that, or it's just a coincidence. Something different about that first day's driving after the fill-up is getting you better mileage, and then it settles back down to the real average.

The temperature of the tank or bladder should not matter, since the car is (so I've heard) just measuring or calculating the amount of gas injected into the engine, irrespective of how much is in the tank.

I'm at about 51 mpg, very near the beginning of a new tank, but it reached 54 during the first day's driving after filling up. Your mileage, by all accounts, will improve significantly as the car gets broken in. Oh, and I didn't run the engine before filling the tank this time.

Hey!!! I wonder if cold gas could give better mileage? Freshly pumped out of the underground storage tank it's cold. Cold gas burns better? Or ignites differently? Or more gets injected than the car thinks???

09-03-2004, 03:23 PM	#1
bigbaldcuban Join Date: Feb 2004 Location: Mansfield, TX Posts: 599 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Stupid question of the day number 2 I've only filled up twice, but I notice that atthe beginning of my tank I'm getting 50/52 MPG. As the tank empties it slowly decreases and ends up about 45 MPG (I'm happy with 45). Is it just a matter of me driving smarter or is this just a normal occurence with the whole bladder/tank thing?

09-03-2004, 06:35 PM	#6
daniel Cat Lovers Against the Bomb Join Date: Feb 2004 Location: Spokane, WA Posts: 8,524 My Car: 2004 Prius Package: #6 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	I'm guessing it's because the car burns more gas during warm-up. You're filling after warm-up, so that first morning's drive gets better mileage. After that, it settles down to the real average. Either that, or it's just a coincidence. Something different about that first day's driving after the fill-up is getting you better mileage, and then it settles back down to the real average. The temperature of the tank or bladder should not matter, since the car is (so I've heard) just measuring or calculating the amount of gas injected into the engine, irrespective of how much is in the tank. I'm at about 51 mpg, very near the beginning of a new tank, but it reached 54 during the first day's driving after filling up. Your mileage, by all accounts, will improve significantly as the car gets broken in. Oh, and I didn't run the engine before filling the tank this time. Hey!!! I wonder if cold gas could give better mileage? Freshly pumped out of the underground storage tank it's cold. Cold gas burns better? Or ignites differently? Or more gets injected than the car thinks??? __________________ Daniel ---------------------- Primary car: Zap Xebra SD: 100% electric car. 1.9 cents per mile, using electrons generated from water power. (The Prius is my gas guzzler, used when I have to travel farther than 35 miles in a day.) "If voting changed anything, they'd make it illegal." -- Emma Goldman "Anyone who has ever looked into the glazed eyes of a soldier dying on the battlefield will think long and hard before starting a war." -- Otto von Bismarck

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Sorry for the stupid question....	BongoSTL	Fuel Economy	4	05-11-2007 09:24 PM
a stupid question	minghi	Prius Tax Credit Discussion	8	04-17-2007 01:37 PM
Really Stupid Question	Kathleen2	Care, Maintenance and Troubleshooting	12	05-13-2006 01:39 AM
Stupid Question	efrench515	Prius Main Forum	3	04-26-2006 12:57 AM
Stupid Question here......	streyle	Audio and Electronics	6	08-09-2004 05:06 PM

09-03-2004, 03:41 PM	#2
rflagg Join Date: Jan 2004 Location: Springfield, VA Posts: 946 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Instantaneous MPG, or average MPG on the Consumption screen? -m.

09-03-2004, 03:47 PM	#3
bruceha_2000 Senior Member Join Date: Jan 2004 Location: South Burlington, VT Posts: 2,127 My Car: 2004 Prius Package: #8 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	How close to "the begining"? Nice warmed up car filled then driven at 35 on the flat will have better mpg than later in the tank when you have had a lot of cold starts, highway driving, etc

09-03-2004, 04:37 PM	#4
bigbaldcuban Join Date: Feb 2004 Location: Mansfield, TX Posts: 599 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	This is on the avg. MPG screen. Both times I fill up it's in the mornings about 6:30. The cars running for about 2 minutes before I get to the Gas station

09-03-2004, 04:58 PM	#5
Marg Senior Member Join Date: Mar 2004 Location: Eastern Ontario, Canada Posts: 153 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Hmmm, interesting. For us, filling with a warm tank yields good numbers at first getting worse over time. Filling with a cold tank yields poor numbers at first, getting gradually better. However, no matter what the conditions are when filling the tank, we nearly always finish the tank at an average of 4.6 litres per 100 km. It's maddenly predictable.