Anyone? The logic is if only fill your tank partially, you'll carry less weight.

The fit's tank is kinda small at 10-11 gallons, and filing half means you have 5 gallons of fuel lighter, which isn't much. The following weeks I might try 3 gallon fillups. Getting 35 mpg, and my round trip to work being 70 miles, I may not be the best person to try it haha. But I'll try it for a few fillups. I'm sure by the end of the week I'll have 3 or 4 numbers and see if it boosts mpg.

 

i never ever fill my tank up more than half way. mostly to get rid of the sloshing. but when i do fill the tank up all the way, my car feels like a slug.

 

Filling up half-way helps. 31mpg in my 02 Civic filling when the gas light was on. 33mpg filling when the tank was half way.

 

I read a list of suggested ways to Eco better and one was never let your tank fall below 1/2. That's the opposite of what you are saying and what I do most of the time. The theory on that is when the tank is less than full the fumes are more and results in more evaporated gas.

I think it would be hard to measure if that is better than never more than 1/2 full and the weight savings as suggested.

BTW That weight savings on avg would be about 30lbs by filling to 1/2 full........


For those that do this, how many gals to you pump each time?

One thing for sure if you do this you have no way to see accurate mpg based on gals really used. Perhaps in the long run the avg will work out???

 

I thik this is only true b/c half of 10 gallons (the fit's size) isn't much. I think starting today for maybe 2 weeks I'll add 2 gallons. If I need a lil more I'll add a lil more (2 gal is EXACTLY my commute length, so if I want to do stuff, i'll need more than 2)

 

The weight of gasoline is roughly 6 pounds, which would give you a savings of 30 lbs or so. Do you really think that is going to make a noticeable difference?

Curb weight = 2741 lbs.
10.8 gallons of gasoline at 6 lbs/gal = 64.8

Crude mathematics would tell you that if your car got 33MPG at a full tank then it would get 33.4MPG weighing 32.4 lbs less. I am sure that is not the most accurate, but it cannot be far off. Also, the fact that so many variable affect your MPG you couldn't justify any findings that go by estimating mileage obtained after filling up.

 

See, what I learned about weight is you can't do simple math like that. The new s2000 CR is 100 lb less than the regular s2000. But on the track it's 2 seconds faster. But then again, s2k CR has tons of other stuff like suspension enhancements.

The 2008 Honda S2000 CR - the Official Honda Autos Web Site

 

Well, we aren't talking about weights influence on track times, BUT you are right in a wrong way. It would be incorrect to make the weight to MPG a direct ratio since there are WAY TOO MANY variables that will affect the outcome. The mathematics that I used would give you the OPTIMAL MPG difference. With that being said, the difference would then be reduced even further by adding other factors that affect mileage.

The only true way to determine this accurately would to be in a totally controlled environment of a lab where every run would be identical.

 

If weight is a concern take out the seats. Those things have got to be heavy. Don't carry around extra junk. 30 pounds of gas isn't that big of a difference......maybe loose 30lbs yourself(if need be). I would rather have the extra gas and use driving techniques. Most people's problem stem from driving techniques and/or the terrain they drive on for their daily commute.

 

No I'd say you are over looking some basic laws of physics. Like I said hard to measure, but without question, reducing the weight by 30lbs will result in improved fuel usage measure in mpg. It could be small but the DIRECTION is certain.........

Force = MASS * Acceleraion

 

I agree with this.

 

This thread gives me an idea

Maybe I'll create a thread based on driver weight vs mileage. I wonder how much worse your mileage is if you're heavy 220lbers vs a 150lber.

 

In my text I never disputed that a reduction in weight would increase MPG. I even said that as a direct ratio it WOULD increase the MPG, but only by four tenths of 1MPG. I then added that there are other variables that would make it almost impossible for the average person to determine if they are getting a significant increase.

 

F – ƒk – bv = ma

Force - kinetic friction force - air drag = mass * acceleration


ƒk and bv are going to make it pretty hard to see appreciable gain, unless you're dropping a good chunk of weight.

 

Okay I don't think it helps haha. I usually get 32-36 mpg



Date Miles Gallons
4/13/08 91.9 2.018
4/14/08 68.0 2.242
4/15/08 90.8 2.148
4/17/08 24.0 1.035
4/17/08 78.6 2.520

Total = 353.3 miles through 10.0 gallons
Avg Mileage = 35.46 mpg

 

Hey Gordio

I repped you for actually testing the idea. It was a good experiment.

 

Thanks.

This exp isn't finished yet, because the last time I calculated mileage was long ago, when my engine was still breaking in. I also used a different mathematical technique. So I still need to measure the mileage of a normal full tank fillup. But i doubt I'll find anything new.

 

It actually helps a little. I've noticed that the meter moves less on the second half of my fuel tank than the first. You might see something like an extra 3 miles on the tank which is about half a mpg.

As pcs0snq stated above. Evaporated gas doesn't really matter with the because the Fit is suppose to be equipted with a Gas Vapor Recovery system. My only advice when doing this is to buy cheap fuel treatment just to make sure your fuel injectors are ok. Also, you don't need much fuel injector cleaner/treatment for 5 gallons, so you can spread the usage over a couple of tanks.

 

I fill up my tank when it reaches half empty just because I try to catch the gas prices before they jump up again.

 

I did a half tank fill up for the first time the other day and I got 31.5mpg. Around 160 miles at 5gallon fillup. I usually fill up at empty and get only 29mpg.