What’s your number??

Carpmart said:
For the drivers amongst the group...Anyone else recognise that optimal speed for your MH/Van/Car? You know, that perfect speed which is the specific engine sweet spot and the impression that one is fully optimising speed/fuel economy/mechanical sympathy.

Driving the MH last weekend I noted it’s cruising sweet spot as 54mph gps speed....

so what’s you’d number then?
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Pedal to the Metal Borr,,, I'd give ya a number but I'm goin sa Fiddlesticksinfast eyes dare not look at the Speedo ?
 
nicholsong said:
I think many of the responses to the OP have not answered the Q about the 'sweet spot'.

I know what he means mechanically, which may not be the same thing as most fuel efficient, driver desire etc.

We have a FIAT 2.8jtd (2003) which has been re-mapped. It also has a quite high-ratio 5th gear, thus the re-map.

It feels comfortable at 2100-2200 rpm. so giving satnav speed of 65-70mph. Anything less and she is labouring, with resultant strain on the drive train, and certainly below 2000rpm I will change down.

The absolute 'sweet spot' mechanically could be at higher rpm but then there is traffic, speed limits and wind friction on our slab-fronted 3m high 'A' Class which reduces performance. So I will accept 2100-2200rpm as being as good as I can get to a 'sweet spot'

Geoff
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This is precisely the point I was making Geoff and a much more elegant articulation than my drivel! ?
 
2200 rpm is sweet in mine about 60 mph
 
Any speed that is legal, and feels comfortable. 2100ish rpm is about 55mph (sat nav, not dash), can sit with the trucks quite happily, and it will give around 25mpg (give or take) with the "toad" on. Not bad IMV for a 3.0L v6 auto, and roughly what the 2.3L Fiat 5 speed, was doing under the same conditions.
 
Our citroen relay conversion ordinarily gets 37mpg (north Yorkshire to fort william) running at 60mph. Last Friday with a tail wind to wooler got 49.5mpg at same mph, coming back on Sunday with a headwind got 38.9mpg at 55-60 mph. Similar conditions re hold ups. Our sweet spot is 55-60 depending on road conditions.

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56 - 60 mph depending on road conditions or if in a hurry. (We are very seldom in a hurry, preferring to enjoy the trip.) Traffic delays en route to a ferry etc may warrant 60mph but normally, if in doubt, we just start out earlier.
 
56 on the clock, 53 sat nav. On remapped 180 auto, same as last 130 manual.
 
It depends really.

Normally 70m-75mph , but if I am driving a performance car and someone goads me into racing mode then red mist dictates the speed.

#nolimits.
 
I tend to go around 60-65 on sat nav cos we’re always late leaving home and want to bag a decent spot at the caravan site ( we mostly use CAMC sites where you can’t go in until midday)
Otherwise I’ve found 55 ish returns a decent mpg.
I must say though , that the average mpg readout on the ducato is very erratic and in my opinion never actually shows an average , just whatever it’s doing at the time
 
The Simpsons said:
Our citroen relay conversion ordinarily gets 37mpg (north Yorkshire to fort william) running at 60mph. Last Friday with a tail wind to wooler got 49.5mpg at same mph, coming back on Sunday with a headwind got 38.9mpg at 55-60 mph. Similar conditions re hold ups. Our sweet spot is 55-60 depending on road conditions.
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49.5mpg at 60mph?!!!
Your van conversion must hav the optional FredFlintstone foot cutouts and the twenny foot mainmast with the fifteen foot mizzen???
and how do ya calculate to 0.5mpg Borr?

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Sweet Spot - - no idea
before we got Cruise control I'd set up to drive at a certain speed speed and the motorhome seemed to have different ideas
though we have noticed on fuel consumption that our 3L 4.25t it doesn't matter whether we do 55 60 or 65 we get 27plus on long trips with tailwind it can go up to 35 mpg BUT over 68 mph it drops off rapidly

So for speed with good mpg 65-68 seems to be the numbers for us
 
Give or take 60 for me, seems to mean I’m not in and out of fuel ⛽️ stations too much, deffo better in Europe though, better straighter roads
 
As an ex lorry driver any vehicle doing less than 56mph (limited speed of my truck) on a motorway was a pain in the arse. Having to overtake vehicles doing these speeds on a 70mph road is not good driving in my eyes and clogs the motoways up with lorries stuck in the middle lane for miles trying to get past slower vehicles.
 
120 mph with no tyre noise...........in my plane :-)
 
2.2 ltr 60 mph

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At 75mph on speedo with CC active I get 55mpg in my 530D xdrive on a long run. 32mpg in town, constant sports mode. Don’t care too much about mpg on the MoHo though but any speed that stops the comfortmatic from “hunting” is good enough for me. Always appears to be at, 40, 50, 60 but if I up the speed by 2 or 3 mph, it settles.
 
I've always found the sweet spot to be at peak torque - whatever the engine.
On my Euro 5 ducato 2.3 its around 1900 rpm, Euro 6 is a little higher, whatever that speed happens to be.
It's also where you will achieve the optimum MPG.

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bigguspeckus said:
49.5mpg at 60mph?!!!
Your van conversion must hav the optional FredFlintstone foot cutouts and the twenny foot mainmast with the fifteen foot mizzen???
and how do ya calculate to 0.5mpg Borr?
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Just keep to 2k revs at max no cruise control. What does help is can converted using internals from swift caravan. Plenty of spare load weight. Prefer running at 1500 revs where possible.
 
To many variables to give overall mpg can only do it each trip. I get better consumption on M2 than M20 which has more hills.

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The Simpsons said:
Our citroen relay conversion ordinarily gets 37mpg (north Yorkshire to fort william) running at 60mph. Last Friday with a tail wind to wooler got 49.5mpg at same mph, coming back on Sunday with a headwind got 38.9mpg at 55-60 mph. Similar conditions re hold ups. Our sweet spot is 55-60 depending on road conditions.
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49.5 mpg ?My conversion is same as yours and has a recon engine.I drive very carefully /short shifting and have never had more than 34/5 MPG. Are you going off the spedo computer readings ? Best I have had on that is 38 mpg.
 
Thanks for all the replies people. Just to reiterate the key point of this topic, every vehicle I have ever owned from has had an optimal cruise speed. It's not about the best mpg, rather it's a speed that the vehicle is just 'unstressed' at... It is kind of a feeling that the rpm for that individual engine, pushing that particular final drive ratio is happiest at.
 
Lanerboy said:
As an ex lorry driver any vehicle doing less than 56mph (limited speed of my truck) on a motorway was a pain in the arse. Having to overtake vehicles doing these speeds on a 70mph road is not good driving in my eyes and clogs the motoways up with lorries stuck in the middle lane for miles trying to get past slower vehicles.
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I can understand that in general being somewhat frustrating. However if the vehicle you are overtaking blends out of their throttle a tad, is aware of the overtake and assists the manoeuvre, it's not really a problem is it? It's dumb ass drivers that are the issue, irrespective of their speed or what they are driving!

Elephant racing (two lorries up hill on their respective marginally different limiters) can go on for miles and is a way bigger issue. Again bad driving..
 
8,200 rev's then the second shift light comes on....oh hang on a minute that's the track car not the MoHo!

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a
Apache said:
I must say though , that the average mpg readout on the ducato is very erratic and in my opinion never actually shows an average , just whatever it’s doing at the time
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That`s the way it is designed, On the Fiat Punto car there is a second and 3rd output accessed by the button on the end of the Stalk which gives overall average and trip average. (y)

I found it useful as an indication of what speed the engine was most efficient.
 
So there’s Trip A Average and Trip B Average. Is there also an overall average ? Never noticed it
 
The Old Man said:
I did get a quote for a retro fit kit but decided as useful as it would be I could live without it.

£400 is almost two months in the van - LOL.
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I fitted one myself on my last car cost about £200. You do pay a penalty in higher fuel consumption as when you get to a hill it floors the throttle.
 
70 on the clock (66 true sat nav speed ).

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