Worried

[Brian GParticipant @briang]

Posted by Michael Gilligan on 27/09/2019 09:05:51:

Sorry, Brian … I think you missed my point

It was about which way up the ratio should be expressed.

There is a good clue in the expression “fuel consumption”

MichaelG.

I think you missed mine as well Michael. If you express fuel consumption as fuel used/work completed lower numbers show higher efficiency, which isn't as obvious to the easily confused as it might be to engineers.

Using miles per gallon also makes the difference between cars appear greater, as whilst 50mpg is 10 more than 40 mpg 0.02 gpm is only 0.005 less than 0.025 gpm. Most people probably wouldn't realise that both of these comparisons are actually the same. Imagine trying to persuade a marketing department to claim the 2020 model "uses 4 teaspoons of petrol less for every mile" instead of "goes 10 miles further on every gallon".

Brian

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Brian G on 27/09/2019 10:57:22:

Posted by Michael Gilligan on 27/09/2019 09:05:51:

Sorry, Brian … I think you missed my point

It was about which way up the ratio should be expressed.

There is a good clue in the expression “fuel consumption”

MichaelG.

I think you missed mine as well Michael. If you express fuel consumption as fuel used/work completed lower numbers show higher efficiency, which isn't as obvious to the easily confused as it might be to engineers.

[ … ]

.

Oh well … Let’s just agree that the whole thing is nonsense anyway

What really matters is running cost: Which should of course include some amortisation of things like the over-used starter motor mentioned by Circlip.

MichaelG.

[Nick WheelerParticipant @nickwheeler]

Metric fuel consumption is measured in litres per 100km not per km, because it gives a sensible, rational number. Just like miles per gallon, rather than gallons per mile.

[R Johns 1Participant @rjohns1]

And to throw the spanner in the works I do miles per pound. My car does 9.45 miles per pound at today's price.

[Mike PooleParticipant @mikepoole82104]

Miles per gallon was straightforward when you bought fuel by the gallon and your car/ bike measured distance in miles as do road signs. Now we have the clumsy conversion of 4.54approx. to find how many gallons we have purchased and the price of a gallon. Luckily most cars now give you a whole set of data concerning consumption in the units you prefer as well as range and travelled distance. Now I entertain myself with seeing how much I can extend the range where once it was how far round you could get the speedo and other daft speed related games.

Mike

[Howard LewisParticipant @howardlewis46836]

Possibly the fairer comparison, vehicle vs vehicle is the unit used by Commercial Motor, to compare commercial vehicles. This was Ton Miles per Gallon..

It made a loaded coach weighing 14 tons, doing 20 mpg (Southdown Motor Services's Leyland Leopards did ), on a long run, look quite economical compared to a 1 ton car doing 40 mpg over the same route!

40 years ago, even a 7.5 ton ULW bus would do 10 mpg around town.

So a modern 44 ton artic, doing 6 mpg is still pretty frugal!

Howard

[SillyOldDufferModerator @sillyoldduffer]

Re MPG, US Gallons are nearly 20% smaller than British Gallons, shock horror. All their cars are gas guzzlers and they don't have Royalty or irony either. Must be unbearable over there, poor things…

[Dave HalfordParticipant @davehalford22513]

Posted by SillyOldDuffer on 27/09/2019 19:14:32:

Re MPG, US Gallons are nearly 20% smaller than British Gallons, shock horror. All their cars are gas guzzlers and they don't have Royalty or irony either. Must be unbearable over there, poor things…

As the owner of a jeep I get the choice of US (or Queen Anne, Yanks are so behind the times) gallon/mile or litre / 100km personally the EU version takes too long to get the result

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Dave Halford on 27/09/2019 23:58:44:

As the owner of a jeep I get the choice of US (or Queen Anne, Yanks are so behind the times) gallon/mile or litre / 100km personally the EU version takes too long to get the result

.

MichaelG.

[Clive HartlandParticipant @clivehartland94829]

It has got to the point now that I no longer worry about the mpg, I just fill up with £20.00 a week and that does it. Even though the car has diagnostic fuel usage I dont bother looking,

here is a point, I have a class 6 engine in my VW. If I use Shell diesel within a few miles the catalyst light comes on and the book tells me I have to do at least 20 miles at 40mph to burn off the rubbish? If I use run of the mill Sainsbury Diesel, no problems. There is a price difference but it is lost by doing the 20 miles to clean the Catalyser unit.

Clive

[blowlampParticipant @blowlamp]

I can get around 25 miles per Ginster on my pushbike. In contrast, a Greggs vegan sausage roll gives higher emissions and lower hill climbing ability.

[Rufus RoughcutParticipant @rufusroughcut]

Our New apprentice was baffled when fractions were mentioned, so we bought him a digital caliper with some on, drives him mad 3/256 ths insanity, on working in dimensions try ordering some think 7 1/2" and 2 mm (21.05 cm) long and see how far that goes.

Also for imperial 1/4" or 0.25 or 250/1000 what your preference? or see if there is a drill 0.635 cm I think the latter would never be on stock and not available to order either.

[RMAParticipant @rma]

Posted by Michael Gilligan on 27/09/2019 10:01:58:

Posted by SillyOldDuffer on 27/09/2019 09:17:52:

[ … ]

Even measuring MPG on the same car is dubious: Traffic Jam, cruising at 56mpg on flat empty motorway, and racing over the Alps produce different results.

[ … ]

.

Which are displayed convincingly [and reasonably accurately] on my dashboard display.

Analogue reading of “instantaneous” mpg

Digital reading of ‘cumulative’ mpg since last reset

Digital reading of “estimated distance available if you continue driving as you have been in the last few minutes”

MichaelG.

Yep, I find this most useful and you can change the units so easily when abroad. I've never bothered to find out to what accuracy the info displayed is, but my guess is pretty spot on. I do use this info over long journeys, and when in the middle of nowhere in France for instance, I drive using the distance to run info. Long gone are the days as a youth I could tell when my car was running short of fuel. It spluttered to a stop! Not much money in those days!!

[Mick B1Participant @mickb1]

Frankly, I think we should be grateful that we've really only 2 major unit systems to worry about.

I can remember reading an artillery manual from the 1790s that had large and extensive conversion tables between weight and dimensional units for different European states (some no longer extant now), further complicated by the fact that units that had 3 or 4 DP conversion factors between different states might still share the same name, or literal translation thereof. For example, IIRC the English Pound differed from both the French Livre and the Prussian Pfund, and both were translated as Pound in the manual…

And there are still Russian rifles from WW1 or thenabouts with their sight ranges calibrated in Arshins.

Edited By Mick B1 on 29/09/2019 10:29:56

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