Full fuel tanks and weight

[obi_waynne]

Does the weight of the fuel you carry in a full tank have much of an effect on your MPG?

"The last bit of fuel in your tank seems to last longer than the first bit" I'm told - this is not my experience though

Do you always brim your tank or do you make regular trips for smaller fill ups? (Do these fill ups take more fuel than you save?)

I do have an opinion on this and had an interesting "debate" with a friend over it so hopefully it will prove to be a lively discussion as we explore this topic .

 

[pgarner]

i dont like to run low - so fill brim it every week.
however i find the 1st half lasts longer

 

[HDi fun]

can't say i've noticed

 

[geraint13]

THE FIRSY HALF OF MY TANK SEEMS TO LAST LONGER than the second. got 50mpg on my recent trip to kent on the way up and got 45 on the way back.

 

[HDi fun]

THE FIRSY HALF OF MY TANK SEEMS TO LAST LONGER than the second. got 50mpg on my recent trip to kent on the way up and got 45 on the way back.

The is quite common, as is the reverse. It's because the tank doesn't have straight sides and the level metering mechanism is not linear.

 

[dpsubaru]

theoretically the fuller the tank the lower the mpg that should be done. a long time ago i used to only fill up half a tank as i thought i could make some ultimate saving on how much fuel was being used as the car was lighter - but any potential savings need to be weighed against the pain in the arse factor of having to go to the petrol station twice as much and the extra cost of that journey to the petrol station - believe it was really a fools errand, now i just ram the thing to the top everytime. The Subaru doesnt need much time between petrol stops in anycase.

 

[franki68]

I would have thought in theory the less fuel the more economical the car is,due to weight,but it probably depends on the car,a range rover is not going to have a noticable effect because it weighs so much int he first place,maybe in a lotus you would see a noticable difference ?

 

[WLBjork]

Pretty much spot on franki68. A modern family car weighs about 1500kg, and probably has about 50kg of fuel when full. That's about 3% of the weight of the car - pretty much negligible.

 

[RobBentley]

I always brim my tank... at 17.4mpg and a 13.8 gallon tank I don't get very far on a tank as it is...

 

[HDi fun]

I always brim my tank... at 17.4mpg and a 13.8 gallon tank I don't get very far on a tank as it is...

Perhaps get the rev counter re-calibrated in pence per minute?

 

[jasio1978]

Perhaps get the rev counter re-calibrated in pence per minute?

Like that one.

 

[RobBentley]

Not a bad idea. As Clarkson once said to an epic exhaust note... "your listening to the sound of money exploding".

 

[turbonutter69]

Perhaps get the rev counter re-calibrated in pence per minute?

Everytime Rob pulls up at the light he not only races the car at the side of him but his petrol gauge too. I bet the petrol gauge goes down faster than the revs go up.

 

[RobBentley]

Everytime Rob pulls up at the light he not only races the car at the side of him but his petrol gauge too. I bet the petrol gauge goes down faster than the revs go up.

haha - very funny . Not even my petrol gauge can beat me, although its close

 

[turbonutter69]

 

[obi_waynne]

It does seem to make sense that you'd save fuel by running around with a maximum of half a tank of fuel.

 

[old-git]

But that means double the trips to fill up. Stuff that.