mpg - who is to blame?

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Fri 2 Oct 2015 14:21
mpg - who is to blame? - rickhardie

The Consumers’ Association (Which?) seem to have taken a stance on car fuel consumption and emissions. In articles, campaigns and petitions the implication seems to be that the difference between “claimed” figures and “real life” values is down to car manufacturers .

Yesterday for example:

“Car makers must come clean on whether they've rigged fuel tests.

The government to immediately publish a timetable for the introduction of fuel tests you can trust.

Redress for those left out of pocket from car maker's inaccurate testing.”

I would be among the first to condemn car manufacturers if they are shown to have “rigged fuel tests”. However, to date, I have seen no evidence presented to support this. The culprit, in my view, is a (now) totally inadequate NEDC test standard imposed by the EC that should have been written more carefully to remove loopholes and updated more regularly to reflect changes in car technology and driving style and habits. Faced with demanding emission targets I would expect manufacturers to use the NEDC standard in their favour wherever possible. The evidence I have so far found online however suggests that even if they exploited all the loopholes to maximum gain it would only account for about 1/3 the disparity between test and real life. The report concluded there was no evidence to support this size of gain though.

Is this a fair view? And if their should be "redress" how should it be assessed?

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Fri 2 Oct 2015 14:37
mpg - who is to blame? - DirtyDieselDogg

Any fool should realize that sellers always "game" the system to their advantage.

For 1 how the heck do "Flash" get away with their downright misleading adverts, over 40 or 50 years, showing a flash empowered mop leaving a startlingly clean stripe across a very dirty floor?

I suppose if one started each stroke of the mop, with a brand new mop, perhaps, but hardly pertinent to real-world mopping.

Plus the disparity of driving abilities and styles could count for 20 to 25%, from 40 years of driving and observation.

Never mind the terrain and weather conditions.

In my case as a 20 odd year old noticing the difference between "hooning" about, or "acting the lig" in a 1725cc Hillman Hunter, compared to sedately driving the 50 odd miles to Belfast on a Sat pm and returning on a Sun pm.

being about 20-25mpg to 40 or over mpg, in the same car.

marcus

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Fri 2 Oct 2015 14:37
mpg - who is to blame? - RobJP

I'd have to agree with you that the NEDC testing protocol is largely to blame.

The problem is that, as soon as you create a test - with penalties/bonuses for failing or passing that test - people or companies will try to 'game' it.

I suppose the only alternative would be to tell senior management for a car manufacturer to drive round a test track until they ran out of fuel - such tests to manage a specified average speed - and to take those results as the 'official' fuel consumption for a car.

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Fri 2 Oct 2015 15:26
mpg - who is to blame? - focussed

I suppose the only alternative would be to tell senior management for a car manufacturer to drive round a test track until they ran out of fuel - such tests to manage a specified average speed - and to take those results as the 'official' fuel consumption for a car.

I totally agree - a fuel consumption test done on rollers in a lab is not relevant.

It should be x laps of the MIRA track at various speeds.

And then a supervised drive across London on a monday morning.

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Fri 2 Oct 2015 16:14
mpg - who is to blame? - Big John

My old Skoda Superb I 1.9 pd(diesel) official combined mpg was 47.9 - I got about 48 - 52

My Skoda Superb II 1.4tsi(petrol) official combined mpg is also 47.9, I seem to get between 45 and 50 although just got 53 out of a tankful through Austria. - the norm seems about 47

Either way not far off the official figures although I never drive accross London

(figures calculated tank -tank)

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Fri 2 Oct 2015 17:04
mpg - who is to blame? - slkfanboy

Maybe you used the onboard computer and VAG have been cheating on those too lol.

Rather depends on journey my 3l jag would do 38mpg on a long trip. Thats not going to happen around town.

The problem with doing a real journey on read is that there are so many things that affect MPG. Like temp, hight above sea level. Weather conditions etc.

The only way would be a goverment testing agency that had their own labs.

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Fri 2 Oct 2015 20:17
mpg - who is to blame? - Big John

Maybe you used the onboard computer and VAG have been cheating on those too lol.


I use the cars odometer for miles driven but not the on board computer for mpg, instead I use number of litres/gallons needed to fill the car. to calculate. Clearly the "click" point can vary but on average it will be correct. The odometer could be wrong of course!!

Out of interest laterly the on board computer was somewhat pessimistic on the Superb I (showed 46 mpg when you had actually done 50) and is fairly acurate on the Superb II petrol although when I drove a diesel Octavia III(1.6) it was somewhat optimistic.

Fuel consumtion figures can be very subjective. We have also a Fiat Panda that is reasonably economical on the urban cycle but very thirsty on the motorway. It's fuel computer is also very optimistic!

Edited by Big John on 02/10/2015 at 20:20

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Fri 2 Oct 2015 18:07
mpg - who is to blame? - alan1302

And then a supervised drive across London on a monday morning.

You will just get different results each Monday even in the same car. If you are going to change the tests make it a good change.

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Sat 3 Oct 2015 22:43
mpg - who is to blame? - focussed

And then a supervised drive across London on a monday morning.

You will just get different results each Monday even in the same car. If you are going to change the tests make it a good change.

Ok - I was half joking there, but seriously, it shouldn't be beyond the wit of an independant testing organisation to devise a standard test in the open air on a test track that mimics town driving from a cold start in cold weather, the worst combination for fuel consumption - use ten different test drivers and average the results would be good- anything except doing it in a lab on rollers, and use a car picked at random from a dealer - no specially prepped test cars.

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Sat 3 Oct 2015 14:12
mpg - who is to blame? - Engineer Andy

I agree - its like giving a footballer an open goal and saying he has to pass the ball to a team mate for the good of the team. Car manufacturers, like F1 teams, normally (except VAG it seems) maximise their cars' abilities within the rules laid down by the regulators by using whatever means are deemed legal, so if the regulators don't do their job properly (as has been the case), then what do they and the politicians expect - it is a cutthroat business, where a few percentage points on mpg, emissions or performance can make a difference of tens of £Ms.

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Sat 3 Oct 2015 15:38
mpg - who is to blame? - RT

I agree - its like giving a footballer an open goal and saying he has to pass the ball to a team mate for the good of the team. Car manufacturers, like F1 teams, normally (except VAG it seems) maximise their cars' abilities within the rules laid down by the regulators by using whatever means are deemed legal, so if the regulators don't do their job properly (as has been the case), then what do they and the politicians expect - it is a cutthroat business, where a few percentage points on mpg, emissions or performance can make a difference of tens of £Ms.

Your example of F1 is quite apt - a number of innovations have been used despite being alleged to be illegal - on investigation they're found to be legal within the wording but not within the spirit of the rules - so the rules are re-worded.

Much like tax-avoidance!

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Sat 3 Oct 2015 22:44
mpg - who is to blame? - Mr Carrot Cake

The only way to do a proper fair test would be on a race track and getting a computer to drive each car in the same fashion.

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Sat 3 Oct 2015 23:19
mpg - who is to blame? - Bolt

The only way to do a proper fair test would be on a race track and getting a computer to drive each car in the same fashion.

I really cannot see how any manufacturer can do an accurate test, as, real world driving, its only an average with too many variables

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Sun 4 Oct 2015 00:28
mpg - who is to blame? - alan1302

The only way to do a proper fair test would be on a race track and getting a computer to drive each car in the same fashion.

Is that fair though? Testing at different times of year, times of day, wet days, windy days, sunny days. The earlier cars out would be at a disadvantage as they will be clearing the track whilst the ones at the end of the day will have a better time of it. There are many, many variables.

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Sun 4 Oct 2015 09:15
mpg - who is to blame? - RT

The only way to do a proper fair test would be on a race track and getting a computer to drive each car in the same fashion.

Is that fair though? Testing at different times of year, times of day, wet days, windy days, sunny days. The earlier cars out would be at a disadvantage as they will be clearing the track whilst the ones at the end of the day will have a better time of it. There are many, many variables.

Agreed - I can't get consistent readings year-on-year despite same driving style, same usage pattern, etc.

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Sun 4 Oct 2015 10:36
mpg - who is to blame? - Andrew-T

<< Testing at different times of year, times of day, wet days, windy days, sunny days. The earlier cars out would be at a disadvantage as they will be clearing the track whilst the ones at the end of the day will have a better time of it. There are many, many variables. >>

So hire an empty airfield and test half a dozen cars simultaneously. Have some fun at the same time ....

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Sun 4 Oct 2015 10:58
mpg - who is to blame? - diddy1234

Just what top gear 'coud' have done. He he

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Sun 4 Oct 2015 11:43
mpg - who is to blame? - Bolt

Just what top gear 'coud' have done. He he

J C is heavier so his car would be less economical ;-)

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Sun 4 Oct 2015 13:24
mpg - who is to blame? - Engineer Andy

Just what top gear 'coud' have done. He he

J C is heavier so his car would be less economical ;-)

I would've thought he was lighter because he' so full of hot air! (not really - just a bit of fun!).

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Sun 4 Oct 2015 12:13
mpg - who is to blame? - Mr Carrot Cake

Just what top gear 'coud' have done. He he

Very true. They could have done a lot more than just mess about. I was never a big fan of Clackson's Top Gear for that reason.

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Sun 4 Oct 2015 13:44
mpg - who is to blame? - Bolt

Just what top gear 'coud' have done. He he

Very true. They could have done a lot more than just mess about. I was never a big fan of Clackson's Top Gear for that reason.

Yes I agree, I would have prefered someone who knew what they were talking about instead of having a weird sense of humour even though some/a lot of people found funny ie comedy of cars rather than car show about the car

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Sun 4 Oct 2015 17:40
mpg - who is to blame? - alan1302

<< Testing at different times of year, times of day, wet days, windy days, sunny days. The earlier cars out would be at a disadvantage as they will be clearing the track whilst the ones at the end of the day will have a better time of it. There are many, many variables. >>

So hire an empty airfield and test half a dozen cars simultaneously. Have some fun at the same time ....

So you don't ant any hills, corners or proper testing then? :-)

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Sun 4 Oct 2015 17:56
mpg - who is to blame? - slkfanboy

My winter mpg is worse than my summer figures. Plus wet weather and many other factors come into play.

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Sun 4 Oct 2015 17:57
mpg - who is to blame? - Andrew-T

<< So you don't ant any hills, corners or proper testing then? :-) >>

If you like. The point is, we're testing mpg, so they all do the same thing in the same conditions.

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Sun 4 Oct 2015 17:59
mpg - who is to blame? - alan1302

<< So you don't ant any hills, corners or proper testing then? :-) >>

If you like. The point is, we're testing mpg, so they all do the same thing in the same conditions.

That's what happens now though. So why change it?

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