Full tank vs. Partial fill ups for Fuel Economy

[jamesqf]

Originally Posted by slowmover

IMO, yeah. Better to fill up weekly no matter how little used.

Weekly? Depends on what you're driving, and how much. These days I could do at least a month, maybe 6 weeks, from fillup to empty, so why lug around the extra weight?

Besides, the cheap station I usually stop at has a discount for cash, so I just feed it a $20 bill, which is better than half a tank and lasts 3 weeks or more.

[California98Civic]

Originally Posted by Old Tele man

...uh, water is 8.3 lbs/gal and gasoline is ~6.1-6.5 lbs/gal (depending upon the ethanol blend).

Yup. You're right. I saw a cite of 8lbs but that's wrong, apparently. Fueleconomy.gov claims 6.3lbs: How can 6 pounds of gasoline create 19 pounds of Carbon dioxide? That truth changes the math significantly but not the conclusion: there are measurable if marginal gains to less gas.

[doomz78]

Good info here. Thanks everyone. The gas station that i go to is at the top of a hill on my way to work. And its never busy cause I leave at 5am. So stopping is no issue. I also live at the top of a mountain so my commute to work is 20.2 km long. On a good day im engine on coasting for 10.6 of those 20.2 km. Thats why I usually get 44mpg on my way in to work. There are 5 lights before i finally get to work. So the drive the other way back home is ....

you guessed it. BRUTAL. I start off with 5 lights, sometimes all green and sometimes all red. Then i have to climb the mountain. I usually average about 34mpg on the way back home. So on an average day i get about 39mpg round trip. On an auto 2006 altima 2.5s i think that's pretty good. So for my original question.. I guess it would be negligible to fill up all the way or just part way. Not enough lights. And alot of coasting.

[Frank Lee]

Search gas tank games...

http://ecomodder.com/forum/182705-post2.html

[larrybuck]

If your life is very urban; go for it, but agree w others..... don't go too low for junk to enter. In theory, this idea plus no spare tire would do urban wonders! (sigh)

[CigaR007]

I gas up when there's more or less 15 % left in tank. The weight factor is negligible IMO, in terms of fuel economy. Plus it makes it easier to manage my budget (lump sum vs scattered random gas bills).