These are just a magazines test results. They have no legal standing.
Like all quoted MPG figures they need to be taken with a pinch of salt.
Just calm down.
Dear 'thunderbird' - thank you for your wise counsel. I do not personally give a fig for what data is published by What Car, as I am more than happy with the performance of our family hatchback, but as a professional electronics engineer, now semi-retired, only working for 3 days a week on average, I have too much time on my hands and so I get a bit worked up when I spot 'glaring data errors' in the media or motoring journals who do not seem to understand the basic laws of physics and do not seem to be at all concerned about publishing data, upon which important vehicle choices may be made, that are clearly anomalous!
If you follow the narrative in the What Car publications and visit their interactive TRUE MPG web page mpg comparison tool, then you will see that they have attempted to characterise every car tested with a carefully monitored 50 mile round trip in each car, under the guidance of an independent consultancy from which they claim to be able to estimate what sort of fuel economy you might expect when driving each of a number of vehicles, inside your chosen comparison group, all under your own favourite motoring conditions! Maybe the old fashioned 'Autocar' method 'brim to brim' measurements throughout a range of both performance and economy tests is still superior to this fairly short '50 mile' round trip test method employed by the what car consultants?
In any event the Honest John Real MPG data base is also available. It records real mpgs reported by hundreds of car owners and is organised on a model by model basis and this is always there for comparitive puposes.
Edited by Firmbutfair on 01/10/2014 at 17:03
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I read test results on mpg. The HJ ones are submitted by users: so utterly without any value - because the users can submit any old rubbish or actually give real life results dependent on journey time, length etc.
Not worth reading anything except the official figures and deducting 20 % or more .
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Over the years What Car have published a load of total carp disguised as Motoring Journalism so why expect the "Real MPG" figs to be any better.
Take this example. Some years ago I was looking for a new motor. The Toyota Auris was on my wish list and that month What car just happened to have a group test including the Auris so I bought it. Test was of a petrol and I was considering the diesel but the remainder should have been relevant. Write up was OK but ultimately did not buy one.
Roll the clock forward a couple of years and the wife is considering a Honda CRV. By some strange coincidence What Car have a group test including that very car, bought the mag. As I sat reading it the published performance data looked very un SUV diesel like so to satisfy my own mind I got some old mags out to look for a comparison with similar cars. Could find none but when I opened the page with the Auris data on guess what, exactly the same figures as they had used in the SUV test.
So had they really tested the SUV's, had they really tested the Auris.
Not bought a copy of What Car since.
So do they really do the "Real MPG" tests or just make them up in the pub.
Who knows. Who's bothered.
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Not worth reading anything except the official figures and deducting 20 % or more
Exactly what I do. Not been disapointed yet. Current cars are 14% and 17% down on the official combined and more or less bang on the Honest John figures.
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The whatcar figures are a pile of dross. I've looked at them previously
As an example, they reckon for my sort of criving, a BMW 320d I'd get 51 mpg, but for a 118d hatchback a lot WORSE economy at 43.5 mpg. Same engine in both, detuned in the 1 series, but a lot lighter car.
As an aside, when we used to have an old-shape 118d, we averaged 53-55 mpg. Our current 325d estate (twin-turbo version of the 320d) averages 45 mpg.
According to HJ's owner-submitted figure, the 118d is 49 mpg, the 325d is 43 mpg (though some of those 325d figures are my own)
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As an aside, when we used to have an old-shape 118d, we averaged 53-55 mpg.
I had a 2008 118d for 5 years. In that time the computer said 52 mpg average. But when you calculated it using the fuel bought and the distance covered it was actually 48 mpg. On a couple of occations when we went on a long trip I zero'd the computer and never saw better than 56 mpg which was about 51 or 52 mpg at the very best.
Think you relied on the lieing computer too much (just like most people).
Edited by skidpan on 01/10/2014 at 17:58
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As an aside, when we used to have an old-shape 118d, we averaged 53-55 mpg.
I had a 2008 118d for 5 years. In that time the computer said 52 mpg average. But when you calculated it using the fuel bought and the distance covered it was actually 48 mpg. On a couple of occations when we went on a long trip I zero'd the computer and never saw better than 56 mpg which was about 51 or 52 mpg at the very best.
Think you relied on the lieing computer too much (just like most people).
Never. I'm a scientist by training, and like far to many of that ilk, I'm not someone who can turn it off when I take off my lab coat at the end of the working day.
Best ever saw was a calculated 62 mpg, on a 536 mile trip (. I knew how far it was by maps and routeplanners, I knew how far the car said it was (544 miles), and I filled up at the end of the journey (up in Scrabster, we were heading over to Orkney) and I'd filled up at the start of the journey too.
Think the wind must have been behind us a bit on the way up, because heading back south we only averaged about 58 mpg (calculated, again)
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Apart from deducting 20% from the official stats, the other rule of thumb I use is:
Average mpg = official urban figures.
Real urban use = urban -20%...
Works pretty well - except for hybrids.
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The whatcar figures are a pile of dross. I've looked at them previously
As an example, they reckon for my sort of criving, a BMW 320d I'd get 51 mpg, but for a 118d hatchback a lot WORSE economy at 43.5 mpg. Same engine in both, detuned in the 1 series, but a lot lighter car.
As an aside, when we used to have an old-shape 118d, we averaged 53-55 mpg. Our current 325d estate (twin-turbo version of the 320d) averages 45 mpg.
According to HJ's owner-submitted figure, the 118d is 49 mpg, the 325d is 43 mpg (though some of those 325d figures are my own)
Thanks RobJP - I too am a scientist and engineer by training and the thing that most upsets me is that What Car go to considerable expense to test each car using, what should, by all appearances, be a sound and reasonably accurate 'scientific method' involving a car full of test equipment, a technician as a passenger, driving over a carefully pre-planned, fixed, 'mixed driving' route of some 50 miles and fully supported by an independent test laboratory namely << www.emissionsanalytics.com >>. They are attempting to measure each car under a range of realistic normal driving conditions and by so doing capture enough essential elements and characteristics of each car to be able to generate a 'look up table of data' from which other driving styles and routes can be extrapolated (estimated).
The overall 'average fuel economy' published on their web site for each car (and now in their printed magazines), is compared side by side with the NEDC govt 'combined' figure and is of course as expected typically 15% to 25% lower than the NEDC figure.
Given the trouble they take to generate TRUE MPG figure for each car it is surprising that the results are so inconsistent e.g. the 'Kia Rio 1.25 Air 5 door Hatchback' should return much the same TRUE MPG average as the almost identical 'Hyundia i20, 1.25, 5 door Hatchback because they use the same Hyundai 1248 cc engine in the same state of tune etc and they both 'weigh in' the same, have similar tyres etc. Therefore to publish that one will return 46 mpg and the other only 36 mpg is clearly anomalous, but What Car does not seem to be concerned about this.
When a wide range of What Car TRUE MPG figures, for what are very similar cars from different manufcaturers, are compared, many enormous and unexpected variances appear which should make the publishers pause to say - what is going wrong !
In other words their test method should yield a result of say 46 mpg as the average figure for most 1.25 litre, normally aspirated, 1080 kg, 5 door hatchbacks with an uncertainty of say plus 2 mpg and minus 4 mpg, which is a 'spread' of 6 mpg around the 46 mpg figure and therefore any tests ath suggest a spread of as much as 10 mpg should be invetigated and not published until the anomaly has been resolved.
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I have now browsed through the Emissiona Analytics web site and I think I may have discovered where the problems lie !
1). Statement of Problem:
Average TRUE MPG figures published by What Car Magazine show glaringly anomalous test result variances of typically 24% (i.e. obvious inconsistencies) between nominally identical types of car from the same manufacturers and even larger and less credible variances between 'similar sized and engined' cars from different manufacturers.. Despite this, What Car Magazine (Haymarket Publications) are inviting the car buying public to make choices based on their 'apparently TRUE' MPG test plan involving just one example of a popular car driven accorining to a fixed plan over the same fixed 50 mile mixed route. Each car is tested using sophisticated, portable, in-car test equipment according to a carefully designed driving plan devised by an independent test organisation called EmissionAnalytics. However data published on the EA-Analytics web site at www.emissionanalytics.com shows much smaller variances namely around 15 % across spread across 26 major european car manufacturers.
2). The EA-Analytics Team of staff include, an ex motor sport technician, a data analyst, a media and arts expert, several ex motoring journalists, a project manager, and some test and calibration technicians - but no professional scientists, professional engineers or statisticians.
My conclusion is that they genuinely do not realise that there is anything wrong with all the anomalous results they are so proudly presenting to the general public as the TRUE MPG figures for many of the cars they have so far tested using their much publicised scheme.
Arguably, the What Car test process is capable of giving a more realistic figure than the NEDC 'CO2 plus triple data point' figures published for each new car by law, but unlike the car manufacturers, they should not have any 'vested interest' in making sure the test results are as good as possible and so are quite happy, indeed quite pleased when they see such large differences between manufacturers, mistakenly believing that they have discovered some startling 'truths' that the public need to know about when choosing a new car!
Unfortunately, relying on a sample of just one car, and then accepting the resultant test figures - even if they are statistically and scientifically highly questionable - and publishing them for all to see - is just not good enough !
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The fuelly website gives an average of about 180 owners usage with a variety of petrol Rios as 38 mpg
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I have always found kia and hyundai to have the most exaggerated official fuel economy figures.
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I have always found kia and hyundai to have the most exaggerated official fuel economy figures.
True, I had a Hyundai Getz 1.3 in the mid noughties and the dealer and What Car estimated the average mpg to be 45 mpg, acceptable in those days. I was lucky to get 40 mpg on a long journey and often struggled to get more than 36 mpg around town. Also the car, for all it was well equipped and decent to drive, developed a whole heap of faults such as rusting alloys( replaced under warranty), air conditioning failure( luckily replaced under warranty), and annoying trim defects. As soon as the five year warranry ended, the clutch died and then the ECU gave up. I thought never again.
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