# How much fuel can I save by losing weight?



## Brock

Will I notice the improvement in fuel consumption if I trim 90kg off my motorhome's weight?

Since acquiring a van with a garage, I am more organised. I have 4 storage boxes in the garage. Three are for domestic things we're likely to use when away for a few days or more. A 4th box holds things needed on the road.

It occurs to me when I use the van for day trips or day visits to friends and family [I don't have a car], I could remove the 3 domestic boxes and save c90kg. I'd then put them back when in touring mode. I know every little helps but I can't really see it helping enough given the van already weighs c3100kgs. I tend to travel with 25l of fresh water, empty waste tanks, and sufficient fuel for the journey plus 20 litres.

How much weight would I need to trim the make a difference such as 2mpg on a trip I would normally achieve 28mpg? My schoolboy maths suggests c220kgs.

Money isn't the issue - one of my sons has challenged me to break the 30mpg barrier without changing driving style. He reckons my current driving style already results in us being burned off by snails.


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## tonka

It's like the people who wont travel with water in their tanks..!!
Ok some may have weight issues but when you have a 3 tonne plus vehicle will 50 - 100 ltrs of water really make a difference.. :wink:


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## 1302

None. I imagine.

And the day you have to drive back home to pick up the boxes you forget will wipe out any, if any, saving 

90kgs is about one person - would that really have any effect?


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## VanFlair

Hi Brock

Of course it will make a difference, will you be able to measure it!! errr not sure.

90kg will be about 2% of you total weight which has to be accelerated but it does not affect the wind resistance which is a constant, if you said that weight and wind resistance were about 50/50 you might expect another 0.25 to 0.3 MPG.

There again might be worse if you only ever go downhill !!.

Martin


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## wakk44

I have checked the mpg with water tank empty and full which is a difference of 120kgs.The difference in fuel consumption was very small,less than 1mpg.I did notice the engine laboured a bit more up hills but not really enough to worry about.

We also never know where we will be overnight,we may find that beautiful wild camping spot,so our fresh water is at least 1/2 full when we set off.


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## tonka

VanFlair said:


> Hi Brock
> 
> Of course it will make a difference, will you be able to measure it!! errr not sure.
> 
> 90kg will be about 2% of you total weight which has to be accelerated but it does not affect the wind resistance which is a constant, if you said that weight and wind resistance were about 50/50 you might expect another 0.25 to 0.3 MPG.
> 
> There again might be worse if you only ever go downhill !!.
> 
> Martin


Plus leave the weight in and you will be heavier to roll downhill !!!
Swings and roundabouts come to mind...


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## rosalan

I am in Spain at the moment and my MPG is reading 31. Before I left home, driving around the UK it read 34MPG.
Is it because I am fully loaded?
Is it because it is hotter here?
Is it a different fuel mixture?

Alan


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## rosalan

I am in Spain at the moment and my MPG is reading 31. Before I left home, driving around the UK it read 34MPG.
Is it because I am fully loaded?
Is it because it is hotter here?
Is it a different fuel mixture?

Alan


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## cabby

Hey Alan,
you don't really believe what the onboard computer tells you surely. :lol: 

sounds as if the only way is to change your driving style Brock

cabby


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## rosalan

Could be right Cabby, the feather I have attached to my right foot is wearing a bit thin; never exceeds 57mph at home or away...... its nice being 'away'!

Alan


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## delawaredandy

In the big scheme of things does 1 or 2 mpg really matter :wink:


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## Zozzer

I always run with empty water tank and empty grey water tank whenever I can, and I do find that I don't use as much fuel. Also, you really notice the weight difference if your tanks are full and have to adjust your driving accordingly.


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## TheNomad

Zozzer said:


> I always run with empty water tank and empty grey water tank whenever I can, and I do find that I don't use as much fuel. Also, you really notice the weight difference if your tanks are full and have to adjust your driving accordingly.


Why?

Don't worry, be happy.

Soz, but I really don't get the fascination with micro-variations in mpg.
When the fuel tank gets low, fill it up. Other than that, just enjoy it. 
I genuinely have no idea what our MH does to the gallon (or litre). Nor did I know what any of our previous MH's did to the gallon.
A slab-fronted, heavy van is always going to crap at fuel economy. Hey ho. Life really is too short.

It is losing FAR more money in depreciation every single day just by sitting on the drive than it is if you do 26.79mpg instead of 28.23 mpg on the very few thousand miles the thing actually gets driven for in a year.

What's the real difference? Twenty quid? 50 quid even? Over an entire year.


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## 1302

TheNomad said:


> Zozzer said:
> 
> 
> 
> 
> I always run with empty water tank and empty grey water tank whenever I can, and I do find that I don't use as much fuel. Also, you really notice the weight difference if your tanks are full and have to adjust your driving accordingly.
> 
> 
> 
> Why?
> 
> What's the real difference? Twenty quid? 50 quid even? Over an entire year.
Click to expand...

I would prefer to arrive with water for theweekend than turn up without for the sake of a couple of euros...


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## 1302

TheNomad said:


> Zozzer said:
> 
> 
> 
> I always run with empty water tank and empty grey water tank whenever I can, and I do find that I don't use as much fuel. Also, you really notice the weight difference if your tanks are full and have to adjust your driving accordingly.
> 
> 
> 
> Why?
> 
> What's the real difference? Twenty quid? 50 quid even? Over an entire year.
Click to expand...

I would prefer to arrive with water for theweekend than turn up without for the sake of a couple of euros...


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## listerdiesel

In the general scheme of things, fuel consumption is not something we worry too much about, with the trailer and engine behind us, we are grossing nearly 6 tonnes, and whatever the cost of the fuel, that's what it will take to get us where we are going. In Holland we are 20% better on fuel than the first part of the A14/A120 when we get back.

Saving a few mpg isn't really practical unless you are able to keep away from motorways etc and keep your speed well down, then you become a hazard to other, faster traffic.

We don't carry any water but the LPG tank is always full.

Peter


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## Scattycat

delawaredandy said:


> In the big scheme of things does 1 or 2 mpg really matter :wink:


On short journeys, No. But on a 6,000km trip probably yes


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## tonka

Scattycat said:


> delawaredandy said:
> 
> 
> 
> In the big scheme of things does 1 or 2 mpg really matter :wink:
> 
> 
> 
> On short journeys, No. But on a 6,000km trip probably yes
Click to expand...

Actually on 6,000 miles (stop that km nonsense lol ) my calculation is that it's about £100 difference.. SAD but the calculator was in my hand..


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## TheNomad

Scattycat said:


> delawaredandy said:
> 
> 
> 
> In the big scheme of things does 1 or 2 mpg really matter :wink:
> 
> 
> 
> On short journeys, No. But on a 6,000km trip probably yes
Click to expand...

Not really.

The difference between say 28mpg and 29 mpg, if consistently achieved over that entire 6,000kms European road-trip is about 22 litres. 
At say €1.30 per litre on the Continent, that's only about 23 quid in total, for that entire high mileage tour.

By comparison, your MH will be depreciating at say £5,000 annually; and other annual costs such as insurance, MOT, servicing, tyres etc etc might add at least another £1,000 to that. 
So if that 6,000kms tour took you four weeks, just your depreciation and other fixed costs will have racked up to £460 in that amount of time.

Mpg really is one of the least significant of all costs in owning/running a Motorhome.

It is only kept artificially above all the other costs in our heads simply because we pay out for some fuel so many more times through the year than for the other, much bigger annual costs and even bigger depreciation cost that we don't think about on a daily/weekly basis.
Fuelling up is a REGULAR cost, so we mistakenly tend to think of mpg differences as a BIG cost (or saving). But really they ain't.


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## Brock

The comments confirmed what I thought - I'm not going to gain 2mph just by losing weight as there is no margin in the loading capacity. Think I'll get out of the challenge by telling my son he suggests his mother loses weight as she is over the norm for a passenger.

Ever since I started caravanning in 1990 before moving to motorhoming in 1974, 28mpg has been the norm whenever I've bothered to measure it. The only time I've gone over 30mpg on a regular basis is in Germany. I don't really bother about the mpg providing it is reasonably consistent.


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## delawaredandy

Tonka you need to get out more, If I managed to save £100 in 6K miles my missus would only blow it on new shoes or dresses what's the point :lol: 

M


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## stewartwebr

The general opinion seems to be 90kg will make no difference to the mpg. My other half was getting worried as I was kicking him off if significant fuel savings could be made.

I never look at mpg as others have said I am driving a 5.5 tonne Motorhome with a 1 tonne car on tow, if I wanted MPG and it other end me I would buy a tent and smart car lol


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## stewartwebr

The general opinion seems to be 90kg will make no difference to the mpg. My other half was getting worried as I was kicking him off if significant fuel savings could be made.

I never look at mpg as others have said I am driving a 5.5 tonne Motorhome with a 1 tonne car on tow, if I wanted MPG and it bothered me I would buy a tent and smart car lol


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## Rapide561

Brock said:


> Will I notice the improvement in fuel consumption if I trim 90kg off my motorhome's weight?
> 
> Since acquiring a van with a garage, I am more organised. I have 4 storage boxes in the garage. Three are for domestic things we're likely to use when away for a few days or more. A 4th box holds things needed on the road.
> 
> It occurs to me when I use the van for day trips or day visits to friends and family [I don't have a car], I could remove the 3 domestic boxes and save c90kg. I'd then put them back when in touring mode. I know every little helps but I can't really see it helping enough given the van already weighs c3100kgs. I tend to travel with 25l of fresh water, empty waste tanks, and sufficient fuel for the journey plus 20 litres.
> 
> How much weight would I need to trim the make a difference such as 2mpg on a trip I would normally achieve 28mpg? My schoolboy maths suggests c220kgs.
> 
> Money isn't the issue - one of my sons has challenged me to break the 30mpg barrier without changing driving style. He reckons my current driving style already results in us being burned off by snails.


In my opinion - no fuel saving. On a car weighing 1000kg, then yes an extra 100kg might help, but on a 3500 or 5000kf motorhome, with the aerodynamics of an Austin Allegro in reverse.....I think not

Speed and drag are the key factors...

Russell


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## Rapide561

Brock said:


> Will I notice the improvement in fuel consumption if I trim 90kg off my motorhome's weight?
> 
> Since acquiring a van with a garage, I am more organised. I have 4 storage boxes in the garage. Three are for domestic things we're likely to use when away for a few days or more. A 4th box holds things needed on the road.
> 
> It occurs to me when I use the van for day trips or day visits to friends and family [I don't have a car], I could remove the 3 domestic boxes and save c90kg. I'd then put them back when in touring mode. I know every little helps but I can't really see it helping enough given the van already weighs c3100kgs. I tend to travel with 25l of fresh water, empty waste tanks, and sufficient fuel for the journey plus 20 litres.
> 
> How much weight would I need to trim the make a difference such as 2mpg on a trip I would normally achieve 28mpg? My schoolboy maths suggests c220kgs.
> 
> Money isn't the issue - one of my sons has challenged me to break the 30mpg barrier without changing driving style. He reckons my current driving style already results in us being burned off by snails.


In my opinion - no fuel saving. On a car weighing 1000kg, then yes an extra 100kg might help, but on a 3500 or 5000kf motorhome, with the aerodynamics of an Austin Allegro in reverse.....I think not

Speed and drag are the key factors...

Russell


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## Pudsey_Bear

Weight will add to the fuel consumption that is obvious as you know, it is the effect of the weight which costs though, if you were to up the tyre pressure a little it would decrease the increased rolling resistance of the tyres, most of your fuel consumption is getting the lump rolling and pushing it through the air, in some respects the additional weight actually helps, as it will push the van down hills, however it works against you going up, but it does act a bit like a flywheel when going along at a steady speed into a head wind as you have the momentum/inertia acting for you, a lighter van would have to use more power, assuming a straight and level road.

I could go into more detail but that's roughly according to Newtons first law.

*Newton's first law of motion states that "An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force." Objects tend to "keep on doing what they're doing." In fact, it is the natural tendency of objects to resist changes in their state of motion. This tendency to resist changes in their state of motion is described as inertia.*

I went and grabbed that to make sure it was acurate.


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## aldra

we've lost 5 stone combined

surely we will not even need Deisal now :lol: :lol: 

before 34 per Gall

Cabby what a pain you are :lol: 

However, a rather nice pain 

aldra


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