Fuel Misers

[Dirk]

[QUOTE 5112740, member: 9609"]is this the reading from the cars computer? or is it a fill to fill calculation taking in distance inaccuracies caused by tyre sizes ?
My wifes Yeti will show an impressive 50 to 55, but its true long term average is 42. (what can you expect from the VW group)[/QUOTE]
The in car readout and the fill to fill calculations in my Peugeot 207 SW generally agree.

 

[raleighnut]

Slip my old 7 series into Sport and stand on the loud pedal and it would drop below 1 MPG for 5 seconds or so.

View: https://youtu.be/OxMxFE37Sxw

 

[DaveReading]

[QUOTE 5112736, member: 9609"] I see no scientific explanation why going up a hill slower would be any more beneficial to driving along a flat road slower.[/QUOTE]

I agree.

 

[User33236]

Slip my old 7 series into Sport and stand on the loud pedal and it would drop below 1 MPG for 5 seconds or so.

If I tried that in my Mustang I used to get EEE on the display. Not sure if it was trying to divide by zero!

 

[Drago]

I agree.

Wind resistance increases as a square of speed, regardless of whether you're on a level road or driving up a hill.

 

[Bonefish Blues]

His is mapped with a water spray onto the (bigger) intercooler, over 400 brake on a 'rolling road' dyno.

I hope it's not the newer 2.5 engine as it will go pop, sure as eggs is little green apples. If it's the old 2.0, then as you were, map away, more the merrier.

 

[gbb]

[QUOTE 5112736, member: 9609"]when you say 'accelerate' do you mean use more power to maintain same speed, or do you actually mean accelerate .[/QUOTE]
I think my words were 'accelerate to maintain speed'...ie use more throttle and of course, more fuel.

 

[gbb]

The in car readout and the fill to fill calculations in my Peugeot 207 SW generally agree.

I did the same on my former Astra, the calculations more or less agreed with the onboard computer.

 

[DaveReading]

[QUOTE 5112870, member: 9609"]I seem to be able to get my head around accelerating (increasing speed) of a vehicle going up a hill being very costly energy wise.[/QUOTE]

When you're going up a hill, you are doing work (= expending energy = using fuel) against two principal forces: wind resistance and gravity.

Wind resistance going uphill is no greater than wind resistance on the flat at the same speed.

The rate of work you are doing against gravity is obviously higher the faster you are climbing - but for a shorter duration. The total amount of work you have done against gravity (= the amount of energy you have expended = the amount of fuel you have used in overcoming gravity) depends only on the height of the hill, not the speed you have climbed it.

 

[Mr Celine]

[QUOTE 5112870, member: 9609"]the thing is though @swansonj is normally very switched on with sciencey things so I'm not ruling him out. he will probably turn out to be right! I'm just not getting my head round why.

I seem to be able to get my head around accelerating (increasing speed) of a vehicle going up a hill being very costly energy wise. And if that is true then conversely de-accelerating whilst ascending to significantly reduce MPG would also be true - I would like to see a proper explanation and some maths to go with it though.

[/QUOTE]

Me too, I'd be happy to see a scientific disproof of this

I drive up a mile long hill at 60mph and @swansonj drives up the same hill at 30mph, my engine is doing work in raising the mass of the vehicle at twice the rate that his engine is. Thus my engine will require to consume fuel at twice the rate his does - but only for half as long. So the actual amount of fuel used would be the same (ignoring the effects of wind resistance and rolling resistance which are obviously greater at speed).

 

[Colin_P]

This is fast turning into plane on conveyor belt type debate.

There is only one way to find out....

 

[Richard A Thackeray]

your into Scania mpg there

Yes, a 3.5 petrol V8, in a boxy, permanent 4wd body, towing a 1300KG van, on the 'rolling' roads that make up the A65
(and the previous miles through Bradford, Shipley, Bingley (pre-bypass!), Keighley to Skipton)

[QUOTE 5112758, member: 9609"]flat to the mat on a big hill at 44t and it can get below 1 [/QUOTE]
Unlike the Thorneycroft Antar, which could manage 4 gallons to the mile, with that big Roll-Royce Meteorite V8 (essentially a 'cut-down' Merlin, at 18 litres)



Mindst you, how about the A.L.E 8870 Trojan heavy haulage tractor, presently the only British owned company making trucks
It's very specialised use though!
http://www.ale-heavylift.com/wp-content/uploads/2017/02/Equipment-Data-Sheet-Trojan-88701.pdf


View: https://www.youtube.com/watch?v=oLAF8jXaFUM

Slip my old 7 series into Sport and stand on the loud pedal and it would drop below 1 MPG for 5 seconds or so.

'Sport-Mode'/Traction Control to off (to allow even more wheelspin) in the XKR. & a full on crush the Wilton effort, could see a similar singular digit

 

[Bonefish Blues]

Sounds like a full on diesel loco!

 

[gbb]

I suspect are other variables in the hill climb scenario as well, it may well be a powerful diesel (or petrol for that matter) may be more efficient on hills than say an underpowered car.
Mine (astra J 1.6 petol) is really quite asthmatic and inclines are instantly felt in the economy figured.

 

[Richard A Thackeray]

Sounds like a full on diesel loco!

Some of their other equipment, the FAUN 8x8 units did use the engines from locomotives, or maybe the UniPower, can't remember which?