Increasing fuel economy by decreasing fuel load!

[giraffe82]

I just read an interesting post about reducing the weight of your vehicle and it basically said that, "For every extra 100 pounds you carry in your vehicle, you reduce gas mileage and fuel economy by roughly 2%.".

Then in one of the follow up posts someone quite cleverly pointed out that by filling your fuel tank to the top you are burning more fuel by carrying fuel!

quote:
"You mention weight. Do you only fill up to 1/2 or 1/4 a tank at the pump in order to save on fuel weight? I mean you shouldn’t waste gas to haul around other gas right?

1 gallon of gasoline equals 5.8 to 6.5 lbs. So if you fill up to a full tank (10 gallons) the avg weight of the tank is more than 60 something lbs concidering that you don’t go down to zero. Filling it up to only halve full yeilds a avg fuel weight of 30 lbs. filling to only a quater tank yield a weight savings of 45+ lbs"

Thought it was an interesting point to share.

[waynne]

Thanks for that. It is a debate I have often had. Will the extra trips to the petrol station compensate for the weight saving? (bear in mind I can never just buy fuel, I have to get a magazine, an exrental DVD, the current pump offer (glowsticks, flasks and blankets etc), a packet of crisps and a chocky bar. I guess I fill up about 3 times a month at the moment. I'll try filling up more often and using less fuel and see if the fuel consumption goes down.

[HDi fun]

it's debatable whether either is correct. I'm not too concerned about the weight (correctly, mass) of a full tank really impinges upon your fuel usage.

I think driving style makes far more difference to your MPG figures.

Anyway, fuel MPG is not the biggest cost of car ownership and usage. Simply owning the things costs you money with depreciation, servicing, consumables (tyres, lamps, pads and discs etc.).

I have a mate who drives around in a 4.4 litre BMW 540i estate. Yes, 19mpg is not impressive. But he only covers 4000 miles per year, so what's the big deal?

And in a car that weighs in at nearly two tons a few extra gallons of petrol (lighter than diesel) it really makes no difference to the already poor economy.

Furthermore, hwo much difference does a full tank make to your fuel usage when you're driving in first gear most of the time?

[waynne]

How'd you know that I drive everywhere in first gear? I just love the way the turbo sings at 6000 rpm!

[giraffe82]

Originally Posted by waynne

How'd you know that I drive everywhere in first gear? I just love the way the turbo sings at 6000 rpm!

hmmm would the car last very long driving everywhere in 1st... haha I can imagine the look on peoples faces as you drive through a busy area flooring it all the time in 1st.

[HDi fun]

No he really does, his daily commute is a city crawl in first gear. Quite why he sought out a manual given the driving style is beyond me, but, there ya go.

And yes, a quad-cam BMW V8 does sound nice at 7000rpm as well.

[waynne]

Not a lot I can say to that is there? Im outed!