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I use less than half a tank of fuel a week but out of habit allways top up to the brim on the weekly shop. Would I gain more in terms of economy if I ran the car between half full and near empty on a regular basis??Any other technical advantages?
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Used to do the same thing with a Landcrab (Morris 1800). The tank was welded into two halves and I found that rust attacked the seams so that when I needed to fill completely there was a leak. Is your tank a complete unit if so this will not apply.
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i have always been told that the weight of the petrol in the tank can make the car burn more fuel, so the best thing to do is have the tank half full (or half empty whichever way you look at it)
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There are upsides and downsides to filling the tank completely.
The most obvious one is the extra weight you are carrying versus the fuel consumption penalty.
Fill the tank completely and you have the smug feeling that you could drive anywhere without stopping for hours!
Also with a full tank of fuel do we drive faster as we have abundant fuel in reserve? I know I certainally do!
Yesterday driving to work down the M5 I took a glance at my fuel guage and it was below the red - somebody else had been driving my car for a couple of days and hadn't topped it up with fuel. So I ambled to work at 50 mph to conserve fuel! Made it there without running out to boot!
Rgds
David
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Just run a *prize-winning* LPG converted Golf GTI with such an unreliable fuel guage that you don't know if the damn thing is half empty/half full/overflowing/bone-dry until you run out.
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I asked a friend on mine in the industry. He said that they used to make fuel tanks out of metal, and that's why grandad never let his car get to empty. All the bits of rust in the tank would ruin the engine.
However, now tanks are made from plastic and in theory there should be very little gunk in it.
I use at least 1 tank of fuel per week, so it doesn't matter to me, but if I were you, I would always keep a quarter tank and only put in what you will use that week - So fill to 3/4 and fill at 1/4.
Hope this helps
Regards
Jonathan
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Why are fuel gauges so vague? It's not uncommon for the reading to vary between 0.3 and 0.7 of a tank within two minutes on a twisting road. Even worse, my wife once managed to run out of diesel in her 205 because of an accumulation of 'bits' in the float tube in the tank. So you can't even rely on the gauge going up and down properly.
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Andrew
This is usually because tanks are anything but a regular shape. They are formed to fit the space available. Therefore it is virtually impossible to simply relate float height to volume remaining in the tank.
Regards
John
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Well, grandad here (by age, not offspring and named as a bad old ****** too!)
does not let tanks get too low. Even if there may be little tiger fur in new tanks there is the matter of gunge sometimes being picked up from a filling station tank.
If one does a rough sum based on the weight of petrol (I think it used to be about 7 pounds per gallon, certainly less than water at 10) and the weight of a car it will be seen that the difference in weight between full and half full is a very small percentage of the whole.
If I fill up I know I can get 250 miles with a margin, without worrying about my petrol gauge which is no better than usual.
Fill up and be happy - eccept about the vindictive tax, of course.
Cheers and beers, Alex
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Tanks are now plastic, so rust isn't a problem.
Regarding carting a lot of weight around, it depends what sort of driving you do. If most of your mileage is constant speed (i.e. otorway etc.) then fill it up. If your journeys are all stop/start then you will be constantly accelerating the extra mass of fuel and that might be noticeable on mpg.
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Er*********** (d*mm, there I go again).
You could probably have some electronics that quite easily converted the varying non linear float reading to a linear gauge reading.
Alternatively you could actually have the gauges marked 1/4, 1/2, 3/4 etc to actually relate to 1/4, 1/2, 3/4 of the tank, rather than 1/4, 1/2, 3/4 of the dial.
But of course you would have to weigh the costs of that against the safety, cost, convenience and environmental benefits for the motorists :-(
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