Shocked by difference in fuel consumption (1 Viewer)

R

Robert Clark

Deleted User
Just did an extended fuel consumption test.

2015 Fiat 2.3 150bhp
6 speed manual - cruise control
Weight 4 tons
Full day driving on the same road

70 mph (2500 revs) - 23mpg
57mph (2000 revs) - 30mpg

A little less speed, saves a lot of fuel
 
Feb 24, 2013
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not long enough
double post, without even pressing anything twice? :)

edit, then I deleted the first when I am sure I was editing the second

there is no hope


double edit, it keeps getting more complicated, the second post then made itself back into a draft, making me out to be a complete liar :) I feel a need for a double post thread (y)
 
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Tootles

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Our old Hymer with the Fiat 2.5 td is returning about 28 MPG on the motorway. Quite pleased with that. Speed held at around 60 MPH.

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Feb 24, 2013
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not long enough
wow, was it the opposite direction? could make a difference maybe

I reckon wind also makes much more difference than we realise, even a few mph head wind must take some pushing out of the way, similarly a gently shove might be helping :)

very rarely get anywhere near 70mph in ours, but also get nowhere near 30mpg either :(
 
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R

Robert Clark

Deleted User
On the motorway only sections of the test, the average mpg increased to 33
It's the off motorway bits at either end that made a difference
I'm sticking to motorways where possible, all those roundabouts and traffic lights in the main roads are costing me loads of fuel, not to mention brake pads and gearbox/clutch wear
 

funflair

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To be fair 23 mpg at 70 is OK, but I am not surprised st the improvement at less than 60.

Ours has never seen 70 and it certainly wouldn't be doing 23 mpg, I can get that at 50-55.

Martin

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Judge Mental

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Just did an extended fuel consumption test.

2015 Fiat 2.3 150bhp
6 speed manual - cruise control
Weight 4 tons
Full day driving on the same road

70 mph (2500 revs) - 23mpg
57mph (2000 revs) - 30mpg

A little less speed, saves a lot of fuel
Yeah but its boring...Also pointless paying for tolls at those speeds:)
 
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R

Robert Clark

Deleted User
To be fair 23 mpg at 70 is OK, but I am not surprised st the improvement at less than 60.

Ours has never seen 70 and it certainly wouldn't be doing 23 mpg, I can get that at 50-55.

Martin
Hi Martin
To be accurate the mpg at 70mpg was only 19
It was the off motorway bits, plus any other slow bits at either end that increased the average to 23

Regards
 
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Robert Clark

Deleted User
Also pointless paying for tolls at those speeds:)
We didn't use tolls in Spain as the motorways were fine
We always use tolls in Italy - it's cheaper than visiting my chiropractor afterwards
We did use tolls in France (got a tag)
£100 from Calais to below Bordeaux
 

vwalan

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whats the rush.
dont use toll roads, dont use motor ways ,try not to use dual carriageways . use small roads , drive through as many villages as you can.
thats the way to travel in a motorhome.
there,s always tomorrow.
might never go over 45mph anywhere.
make big long lines of cars behind .

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Charlie

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Yeah but its boring...Also pointless paying for tolls at those speeds:)

It's boring yes but also very surprising how little time it actually adds to a journey even long ones !

All engines have a sweet spot at which they return best MPG... Find is and stick to it and economy soars ..

Me ? To daft to do it I go Harry flatters everywhere and pay for it at the pumps ...
 
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Robert Clark

Deleted User
whats the rush.
dont use toll roads, dont use motor ways ,try not to use dual carriageways . use small roads , drive through as many villages as you can.
thats the way to travel in a motorhome.
there,s always tomorrow.
might never go over 45mph anywhere.
make big long lines of cars behind .

The 'Rush' is that we only have 3 weeks per trip - so getting there needs to be quick and stress free

While you're holding up the traffic in Calais, we're enjoying a glass on Sangria in the sun in Spain. (y)

Horses for courses I guess

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vwalan

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no i dont use the calais crossing . i live 30 mls from plymouth so use ferry from there to santander .
its cheaper by along way for me .
and i,m there in less than 24hrs .
its nice down here now just north of alicante . mind its got abit cloudy in the last half an hour.
 
Feb 16, 2013
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We have the 2.3 engine, and when first had it checked and checked, and couldn't get anything out of the 26/28 range, whether toddeling along or going eighty down the motorway, didn't find anything made the slightest bit of difference , so never bother now, and can gauantee it will average out at 100 miles for every quarter of a tank, so fill up when we get to around 380 miles never fails.

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Flamenca

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Our old Hymer with the Fiat 2.5 td is returning about 28 MPG on the motorway. Quite pleased with that. Speed held at around 60 MPH.

My old Hymer 2.5td has averaged 26 mpg over the last 4,500 miles. Similarly, I rarely exceed 60mph and mainly drive at HGV speeds on dual carriageways/motorways.
 
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Lenny HB

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You figures are about what I would expect as manufacturers optimise fuel consumption for 90 kph (56 mph) as that is the figures used in the EU tests that they quote in their advertising blurb.
We don't use Autoroutes in France, well OK if they are free. Agree about Italy, on the way to Greece did the last 50 miles along the coast bone shaking experience best avoided.
 

colinw

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Only a computer figure ( usually reads 2 mph optimistic ) . this was after a long spell on French A roads through Carcassonne down to Narbonne at 50mph ish . didn't hold anybody up , just enjoyable driving experience taking in the views .
Actual mpg was 31.86 over 3800 miles on a new engine , 2.3 , 130bhp , 3400kg. Low profile .

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Sep 16, 2010
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Normal driving for us is 65 -----75mph on the way down to Dover on dual carriageways.
Then, once in France, it all slows down to 50 to 60, no matter whether we are heading for, Italy, Spain or Greece.
Got a 2014 2.3 ltr 130bhp at 3.500kg low profile.. Done 12,000 miles so far and have got about 28 to 30 mpg..
Happy with that..
Mitch. (y)
 

Badknee

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If you can stay awake through James May's diatribe on the Bugatti Veyron he explains the need for more power to get through the air. The faster you are going the more air you need to shift out of your way so to do higher speeds the more power you have to ask of your engine. Naturally more power, more fuel. :D
 

Tootles

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If you can stay awake through James May's diatribe on the Bugatti Veyron he explains the need for more power to get through the air. The faster you are going the more air you need to shift out of your way so to do higher speeds the more power you have to ask of your engine. Naturally more power, more fuel. :D
I'm amazed!! That PHd you got in proctology has really paid dividends............:Eeek:

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2657

Deleted User
I'm amazed!! That PHd you got in proctology has really paid dividends............:Eeek:

Proctology...had to look it up, thanks to google:)

Here's a bit more........drag force is proportional to velocity squared

57 mph.....drag 3250

70mph....drag 4900

in other words 50 % increase in drag, other factors will affect fuel consumption so a 30% decrease in fuel consumption seems OK.
 

Steve devon

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Just did an extended fuel consumption test.

2015 Fiat 2.3 150bhp
6 speed manual - cruise control
Weight 4 tons
Full day driving on the same road

70 mph (2500 revs) - 23mpg
57mph (2000 revs) - 30mpg

A little less speed, saves a lot of fuel
We run with the sat nav and dash cam showing the speed. In truth they both show the true speed is four mph lower than what the van speedo says, so your 70 mph is 66, and 57 is 53. We travel at a true 62 mph in a 4.3 ton scout, and getting 25.5 mpg

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Steve

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i am somewhat amassed at the speeds some of us drive at, each to their own so not a get at.
me 55mph most of the time.
Steve
 

Badknee

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When JM had the Bugatti up over 200mph he had done the calcs and it was incredible how much power was needed. To roll the car along the power was tiny compared to the force needed to part the air.

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