Would we get better mileage runing 1/4 tank than always filling up?

[trebuchet03]

I agree with the comments on the extra fuel ups etc.....

But it's a bit misleading to say 100 pounds is insignificant in the grand scheme of things... If 100 pounds isn't bad - why don't I just leave golf clubs and bowling balls in my trunk... I mean, as long as it's not more than 100 pounds, it's insignificant And really, what's 20 more pounds after that? It's less than a percent increase in weight... If we're going to tell people to remove as much weight as possible, but at the same time tell them 100 pounds is insignificant - it's just a confusing mixed message

[rh77]

Originally Posted by trebuchet03

I agree with the comments on the extra fuel ups etc.....

But it's a bit misleading to say 100 pounds is insignificant in the grand scheme of things... If 100 pounds isn't bad - why don't I just leave golf clubs and bowling balls in my trunk... I mean, as long as it's not more than 100 pounds, it's insignificant And really, what's 20 more pounds after that? It's less than a percent increase in weight... If we're going to tell people to remove as much weight as possible, but at the same time tell them 100 pounds is insignificant - it's just a confusing mixed message

You golf and bowl. That's awesome dude!

I'm most concerned about the evaporative effects of filling more often. Besides, it's hard to calculate FE without a true fillup.

RH77

[trebuchet03]

Originally Posted by rh77

You golf and bowl. That's awesome dude!

I'm most concerned about the evaporative effects of filling more often. Besides, it's hard to calculate FE without a true fillup.

RH77

Hehehe.... I know enough to golf... but am not a golfer And I suck at the bowling... I was just trying to think of things someone might leave in their trunk that happen to be heavy :P

[DarbyWalters]

Well Diesel does not have the same "vapor" attributes as Gas...might not be a factor at all. Since most of my driving is "city", the 108 pounds or so might make a measureable difference...easiest way to lose 100# in my opinion.

[trebuchet03]

Originally Posted by theclencher

it's like every damn thing in engineering- a compromise tween diametrically opposing goals

I love when the design requirements include these two things "Top of the line" and "lowest cost available"

S/he who puts a number to the budget first, loses

[JanGeo]

The only critical point that may be affected is if you have enough weight to coast down hill on certain roads without burning gas that would require you to put it in gear if you were lighter then it could save some gas.

[Erdrick]

DarbyWalters: Diesel is great because it has more energy in it than gasoline. This allows for people to travel further on a tank of diesel than they would on a similarly-sized tank of gasoline. As others have mentioned, having to fill up less has benefits.

I personally wouldn't consider doing partial fill ups ever. First off, you will never know what your actual FE is. Second it is a hassle to pump diesel. Third, you wouldn't be able to make long trips as efficiently. It would have to be some really big gains to sway me to change my mind on this.

Something to think about is how the fuel would slosh around more if the tank were less than full. Whether this kinetic energy would be a big burden, I am not sure. It definitely does have some sort of impact though. Just probably not quantifiable.

[DarbyWalters]

My thoughts were 1/4 tank fills < maybe five or six in a row> then a FILL UP to check MPGs. I would only fill up other times when going on a trip longer than 200 miles. Since I seem to do 95&#37; city...it might make a small diff. 108# less weight over 5 1/4 tanks at 150 per 1/4 would be 108#'s or less over 750 miles.

[DarbyWalters]

Yeah, but this is as easy as just adding the extra fuel "LOAD"...used to race for Mazda and "fuel loads" were very important for acceleration and handling/tire wear

[8307c4]

In the quest for great mpg me thinks we should take into consideration all of the other factors involved, what sense is there in squeezing out an extra mile or 3 out of the vehicle if it costs as much or more petrol in other ways?

I can agree with extreme hyper methods only for purposes of competition, but I highly disagree with using such tactics on the road, practical considerations and common sense should be used to gain the best compromise so as to achieve the lowest overall cost.

One of the biggest fuel wasters is fueling itself, pulling into a gas station eats mpg and consumes far more fuel than continuing to drive, one reason the only time I squeeze the fuel trigger is to fill'er up.

My attitude is what good does it do to run a car 100 pounds low if I have to fill up 4 times vs. filling up once? That's the equation needs to be studied, you'll want to compare total mpg between the two methods, long term.
In my case TIME is also a factor, my time is not free, so it depends how highly you value your time but it costs ~10 minutes per fueling session, that's in addition to the mpg loss.
Then, even with an electric fuel pump if there is more fuel in the tank then there is more gravity-based pressure at the outlet.
Last but not least I don't play games with the fuel gauge, that joker gets to 1/4 and it means FUEL me and NOW, I'll be d*&&#37; if I'm going to sit on the side of the road looking like an idiot because I ran out of fuel, y'all can forget that joke.

I believe all of this outweighs the benefit of riding low fuel, another exception is if you know there exist 3 gallons in the tank at 1/4 tank and you only need to go 20 miles, you know, use your best judgment here.

Spoiler (as in, I've done did the comparison tests irl):
With the exception of competition I drive until the gauge runs low, then I fill'er up, yes, always.