MSE News: Government miles-per-gallon car figures 'unreliable'

edited 30 November -1 at 1:00AM in Motoring
67 replies 6.2K views
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  • LumLum Forumite
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    MeanParent wrote: »
    This is a real problem for company car drivers who are refunded mileage by their employers with rates set by HMRC which are based on these inaccurate figures.

    This means that many are seriously out of pocket and there is nothing that can be done. (I have contacted HMRC about this as my car costs 25 pence per mile in fuel but can only claim back 19 pence per mile).

    It actually works out well for the majority of company car drivers, but yes your system does seem somewhat unfair.

    The reason it works well is because CO2 emissions are directly related to fuel consumption and these artificially inflated MPG figures translate to lower CO2 figures and thus lower company car tax.

    My Mondeo Econetic, supposedly gets 64mpg and emits 139 g/km of CO2, funny how the next CO2 tax band starts at 140 g/km isn't it? In practice I get about 41mpg according to the onboard computer.

    One thing worth noting is that the official test has the gear changes performed at pre-set RPMs, unless the car is fitted with a shift light, in which case they change gear at the time specified by the light. This means that the manufacturers can get better figures simply by adding a bit of sofware and a bulb on the dashboard. In my Mondeo often if you change when the light advises the engine will end up labouring at too low an RPM, so I tend to ignore it. I don't mind it though as that stupid bulb is saving me a fair bit of money in company car tax!
  • Ultrasonic wrote: »
    You'd exceed it a hell of a lot more if you drove at 70 mph... (The air resistance at 90 mph is huge, and to be honest I'm astonished you're exceeding any quoted efficiency at that speed.)
    Driving along German autobahns one often sees Porsches gliding past at 250kmh (yes really). I wonder what mpg they get!!!!
  • patman99patman99 Forumite
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    I would be pleased to obtain even 60 mpg, so if the true usage is indeed 71mpg+, I will over the moon.
    I now have an Ipad app that allows me to log the fuel I put-in along with the litres and mileage. It then works-out the on-going cost per mile and mpg. Only just started using it, so will know just how accurate the onboard computer is after 6 months of motoring.
    For comparison, the Focus used 1.2 a tank of fuel for the same mileage.
    Never Knowingly Understood.

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  • chris-jchris-j Forumite
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    No news really. Would prefer Whatcar to do investigation into why government and council's are so obsessed with creating hold ups and jams which are bad for mpg, therefore bad for emissions and the environment.
    In past few years councils in Scotland seem to have policy of paving over the inshots for bus stops and instead having buses stop on carriageway causing queues, no proper ongoing review of junctions to adjust traffic light settings, etc, no investigations into traffic flow on major roads/motorways (e.g stuck in jam for 2 miles then suddenly road completely clear). We should be actively working on better traffic flow but car hating politicians are too easily led by green lobby who are actually adding to problem.
    Apologies for going a bit off topic.
  • yonkyonk Forumite
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    Relative designs cars and he says that the car's engine management system knows when it's on test and powers down anything unnecessary for the test. Obv a bit more complicated than this but essentially, they run the engine lean for the test and therefore it's not real life at all.

    Totally agree about making roads less obstructed. Different relative was a high ranking engineer in London and his dept had all the lights working in "green waves" years ago. He retired and all the phasing was changed...

    MSE should be concentrating on the message that air quality is the 2nd biggest killer of people in the UK and getting people to turn their engines off when stationary would go a long way to help with this.

    If as many people were getting killed by the railways, things would have been done ages ago.
  • FATBALLZFATBALLZ Forumite
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    The figures are certainly accurate for my car, 33mpg urban, 53mpg extra urban, I do 1/3 urban and 2/3 non-urban, so I should get approx 47mpg for my usage, I have a record of my MPG spanning the entire of 2011, and it averages 48mpg. Note the lowest figures are in winter at around 45mpg, and in August I was getting 51mpg (in fact my record for one journey was 57mpg).

    It's all to do with driving style.
  • LumLum Forumite
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    yonk wrote: »
    MSE should be concentrating on the message that air quality is the 2nd biggest killer of people in the UK and getting people to turn their engines off when stationary would go a long way to help with this.

    It's a nice idea in theory but it has a number of problems. It's particularly problematic if you make it a legal requirement as was proposed a few years back.

    1) What happens to emissions, and traffic flow, when the lights go green, everyone restarts their engines, and nobody moves because the 1987 Ford Escort at the front of the queue has failed to restart.

    2) We would really need countdown timers on our red lights as stopping and then immediately restarting actually puts out more emissions

    3) There are some cars which, in the owners manual, tell you not to stop and start it until the engine is fully warmed up, otherwise the engine will flood and it wont start again. The Mazda RX8 and Nissan 200SX are two examples.

    If they ever do bring this in as a law, I'm going to buy shares in a company that refurbishes starter motors :)
  • UltrasonicUltrasonic Forumite
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    yonk wrote: »
    MSE should be concentrating on the message that air quality is the 2nd biggest killer of people in the UK...

    yonk - I was rather surprised by this statement so just had a quick search for research to back it up. Did you mean in London rather than in the UK? I can find a few environmental sites making that statement, although I can't quickly find the research it is hopefully based on.
  • Kite2010Kite2010 Forumite
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    chris-j wrote: »
    No news really. Would prefer Whatcar to do investigation into why government and council's are so obsessed with creating hold ups and jams which are bad for mpg, therefore bad for emissions and the environment.
    In past few years councils in Scotland seem to have policy of paving over the inshots for bus stops and instead having buses stop on carriageway causing queues, no proper ongoing review of junctions to adjust traffic light settings, etc, no investigations into traffic flow on major roads/motorways (e.g stuck in jam for 2 miles then suddenly road completely clear). We should be actively working on better traffic flow but car hating politicians are too easily led by green lobby who are actually adding to problem.
    Apologies for going a bit off topic.

    Moving the bus-stops into the main carriageway is probably a result of the bus drivers complaining that vehicles were not allowing them out of the lay-by when they were ready to depart. So to solve a problem they created another problem.
  • HappyMJHappyMJ Forumite
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    I've spent 3 weeks driving a brand new 2012 Kia Picanto 2 Ecodynamics 1.25L car. Supposed to be 65mpg. So far £40 of fuel has been put into the car and has travelled 300 miles with a mix of urban and non-urban and now on empty. Average price paid £1.40 per litre. By my calculation I think that's around 43mpg.
    :footie:
    :p Regular savers earn 6% interest (HSBC, First Direct, M&S) :p Loans cost 2.9% per year (Nationwide) = FREE money. :p
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