back to article UK gov offers car CO2 rankings by class

The UK government has set up a website advising consumers on which cars are the greenest. The new "Best on CO2 Rankings" webpage uses What Car? magazine's system of classification, breaking motors down into the following groups: Supermini, Small family, Family, Estate, MPV, Compact Executive, Executive, Coupe, Open-top, Hot …


This topic is closed for new posts.
  1. Anonymous Coward
    Anonymous Coward

    More CO2 is better


    Isn't the combustion a conversion of hydrocarbons & atmospheric air to carbon dioxide, water and heat?

    So CO2 emissions is a direct function of the fuel consumption figure?

    So if anything, a car that outputs more CO2 is better than a car that output less for the same amount of petrol. Because the car that is outputting less CO2 is burning less efficiently, and carbon monoxide, methane and other partial combustion products are worse greenhouse gases than CO2? So you really want the car to produce as much CO2 for a litre of fuel as possible.

    So what does this number tell you exactly? That the manufacturer has made the car burn fuel inefficiently in order to reduce CO2 emissions and score better on this test at the expense of a higher mpg?

    Better to buy the one with the best mpg and use it as infrequently as you can.

  2. Matt Hamilton

    Or just not buy a new car....

    Unless your car is a complete wreck, sticking with it, or buying a second hand car will ultimately be more environmentally friendly than the worlds car producers building yet another car.

  3. James Pickett

    Low tax

    There must be plenty of motorbikes that produce less than 100g/km of CO2. Can I have a refund..?

  4. Matthew

    C Charge

    So, do the lower emission non-hybrid vehicles get free access to Ken's Congestion Charge zone like the hybrids, or is this further evidence that the CC is just Ken's Tax?

  5. Anonymous Coward
    Anonymous Coward

    MINI Diesel

    I think if you look at the new MINI diesel you'll see that while its CO2 levels are the same as a Prius' it has far better fuel economy so therefore is burning its fuel more efficiently as well.

    The Prius is, fundamentally, a flawed car that survives solely on hype from Government, PR obssessed celebs and stupid people.

  6. Jim Coe

    I'm confused

    I have always been at a loss to understand how these figures are arrived at.

    How can it be that my gas guzzler produces at least 1500gm of CO2 on a 10km journey whilst using less than 1150gm of fuel ( I don't know the exact specific gravity of unleaded petrol)?

    If we are surrounded by such huge volumes of CO2, it will be dangerous to kneel down soon, as near the poisoned lakes in Africa.

  7. Anonymous Coward
    Anonymous Coward

    Interesting but flawed

    This is interesting data, but it misses possibly the largest component of CO2 emissions related to car use - the CO2 produced during the car's manufacture. I suspect that if this were included the Prius, with its two engines, would slip further down the list.

    Also, why do people insist on referring to all-electric vehicles as the holy grail of zero carbon emission? Surely the CO2 is just coming out of a power station instead?

  8. Chris Collins

    CO2 irrelevant

    *cough* Biodiesel *cough*. Surely Kensington could buy any number of diesel Bentleys if they ran on the rapeseed oil we subsidise French farmers to produce through our taxes. Then the Arabs could have their sand back and CO2 levels would be irrelevant.

    Erm, sorry, I just said something really stupid there.

  9. leslie


    Older vehicles are not that bad, simply because once you have removed all the hype, new engines are not that much better, its a few percent, which is nothing when you consider how much carbon was thrown into the atmosphere to not only build these new cars, but to test, and design, 1000's of man hours at power hungry computers, and all these designers in offices with lighting, and heating / aircon, and then the shop floor workers, heating/lighting/aircon, all those 1000's of people designing a 2% better car by driving to work in their old cars....... the big picture simply proves its not been worthwhile.........

    Of course not that they have designed them, to make it seem worthwhile, we have to destroy our old cars, which creats more carbon, to build the newones, more carbon again..

  10. Anonymous Coward
    Anonymous Coward

    Diesel v Prius

    The diesle may use less fuel but it may produce more CO2, bucause Diesle has longer hydocarbon chains than petrol. This is why CO2 is usefull, because you can see how much polution diffrent types of fuel produce.

  11. Pascal Monett Silver badge

    New cars are better

    Whatever the emission level of the new car you chose, it will most likely be anyway better than the 5-year-old car you have now. Constant improvements are made on engines and combustion technology, and five years is enough to see them come to market.

    So, if you really are green, either find a way to not need a car, or renew your vehicle in less than seven years. Anyone who keeps a car for more than that should not tout any green credentials as far as motoring is concerned.

    Of course, if you're one of the oafs that has a spotless, shiny 4x4, then this whole article and comment thread is useless to you anyway.

  12. John Stag

    "Green cars" - an oxymoron?

    }"The Prius is, fundamentally, a flawed car that survives

    } solely on hype from Government, PR obssessed celebs

    } and stupid people."


    }"why do people insist on referring to all-electric vehicles as

    } the holy grail of zero carbon emission? Surely the CO2 is

    }" just coming out of a power station instead?"

    Nuclear power stations (for example) don't produce CO2.

  13. Anonymous Coward
    Anonymous Coward

    Re: I'm Confused

    "How can it be that my gas guzzler produces at least 1500gm of CO2 on a 10km journey whilst using less than 1150gm of fuel ( I don't know the exact specific gravity of unleaded petrol)?"

    Because the CO2 comprises Carbon from the fuel burnt and Oxygen from the air. The Oxygen accounts for nearly 70% of the mass of CO2 produced.

  14. Altis

    But this info is not new...

    For years now, Vehicle Excise Duty (VED or road tax) has been based on emissions. The manufacturers have to have all their cars tested and the information is stored in a government database. It has been available for years on the VED website. Just download an XLS version and then sort on the emissions column - or any that takes your fancy:

  15. Kevin Johnston

    Alternative Fuels

    My car has been converted to run on LPG and according to the gas analyser on the latest MOT it passed, the test unit had problems lifting the needle of the bottom end stop and shows a meager 0.01% on CO (0.2% max permitted) and 5ppm on the HC test (200ppm max permitted). Now if only the government permitted vehicles first registered before 2003 to qualify for the reduced road tax this would help me as much as it does the environment.

    At least I am paying less per mile than I did on unleaded.

  16. Chris Johnson

    Ha, Suzuki Not even mentioned

    My "Large" 4X4 (I have a tall family and need the space and my partner finds it easier to get in and out of) does not appear on the list.

    I can't even search the site for more makes of vehicles


  17. Anonymous Coward
    Anonymous Coward

    Greener Than Thou

    Surely if you want to be that you get a pushbike?

  18. Anonymous Coward
    Anonymous Coward

    It's all B*ll*cks

    To be honest, who really gives a sh*t.

    People have trouble doing the math.

    In a hundred we'll all be suffering from glabal warming, but how as Oil, Gas and coal reserves are set to decline in usage to it starting to run out in the next 50. Therefore, less fuel = less co2= less Global warming.

    So sod the kids, fire up the eninges and enjoy it before we start herding goats and living decaying cities. The kids will only shove you in a home anyway....

  19. Anonymous Coward
    Anonymous Coward

    All this talk about CO2 missing a major point...

    Global warming is caused by releasing "new" CO2 into the atmosphere. By "new" I mean CO2 that has been happily trapped under the surface of the planet for a million years bothering nobody until it was discovered by BP/Texaco etc.

    Personally I'm quite happy with the CO2 my 10 year old BMW 325 TDS chucks out the back, mainly as most of it comes from second hand rape seen oil I get from the local pub. The only CO2 I release into the air was the CO2 the oil seed rape plant absorbed a few months earlier.

    I might chuck out bucket loads of CO2, but they'd all be nice new ones, not nasty old ones.

  20. Anonymous Coward
    Anonymous Coward

    Re: Re: I'm confused

    Actually oxygen is more than 70% of the weight of CO2.

    Carbon has an atomic weight of 12, Oxygen 16.

    So CO2 is 12+16+16 = 44



    A. Pedant.

    P.S. And no comming back and arguing that C is actually 12.0107, and O is 15.997... I know, I know!

  21. Liz

    More CO2 is NOT better

    "So what does this number tell you exactly? That the manufacturer has made the car burn fuel inefficiently in order to reduce CO2 emissions and score better on this test at the expense of a higher mpg?"

    I don't think so - the CO2 figures are per km driven. I imagine that a lot of the improvements in CO2 figures are really improvements in mpg.

  22. Anonymous Coward
    Anonymous Coward

    RE: Ha, Suzuki Not even mentioned

    > My "Large" 4X4 (I have a tall family and need the space and my partner finds it easier to get in and out of) does not appear on the list.

    Try having a look here - basically the same data, but you can pick any car rather than just the top 10...

  23. Anonymous Coward
    Anonymous Coward

    Why only top 10?

    If the gov are trying to get ppl to think about what there buying then they need to give more infomation and not just the top 10 so ppl can make a more informed decision.

  24. cottonfoo

    Illegal performance levels

    What are they?

  25. Terry Barr

    Test themslves rubbish/fraudulant ?

    I notice somehwre recently that one or two of the ultra econnomical small cars gave much better MPG figurse than the Prius but worse CO2 figures. How can a car uses less fuel for a given distance but produces more CO2 in the same distance ?

    Ther was a story around 30 somethiing years ago that the emission testing cycle was devised so that only a car fitted with a platinum catalyst afterburner could comply with the requirements and that most of the worlds platinum reserves were controlled by a European politician. But of course, in those days we new that western politicians were all honest.

  26. Michael

    CO2 can weigh more than fuel burned

    I don't have the weights off the top of my head, but burning fuel strips off hydrogen (light), and adds oxygen (heavy) to make CO2. So a complete conversion of the carbon in the fuel to CO2 will put out more grams of CO2 than the original fuel weighed.

  27. Paul


    what about the Tesla or Think electric car?

  28. Steve Roper

    Biofuel not viable in long term

    The problem with the biofuel solution espoused by some here (rapeseed oil etc) is the acreage requirement per producible litre. I'm not sure of the exact figures, but I do know that if everybody who has a car ran it on biofuel most of the world's arable land would have to be given over to fuel crops, on top of our food-growing requirements. The resulting monoculture would in itself be devastating to the environment and natural habitats.

    Electric cars and green power from multiple sources (wind, hydro, geothermal and solar, with nuclear filling in the requirement gap) is the optimal solution for the foreseeable future. Yes, nuclear fission does produce Plutonium, so the sooner we get sustainable controllable fusion, which produces only inert helium, the sooner we can do away with this rather nasty tech as well.

    But then we'll have to probably start worrying about helium emissions... people in the future might all end up with squeaky voices!

  29. Anonymous Coward
    Anonymous Coward

    Another Government red herring

    "Every time I hear a new born baby cry, or touch a leaf, or see the sky, I think of all the carbon dioxide in the atmosphere".

    Wake up people - this CO2, Man-made Global warming, we're all going to drown unless we do something now, etc., etc. is the biggest scam since fires in 3 buildings 'caused' them to collapse a few Septembers ago.

    Taxing C02 emissions is as close as you can get to putting a tax on the air we breathe. It is a great money-spinner for any unscrupulous government and goes a long way to making damn sure that underdeveloped third-world countries stay that way.

    By all means buy a low C02 emitting vehicle, but please realize that with "Peak Oil" just around the corner the price of fossil fuels will go through the roof. This will cause the price of anything that is transported anywhere to rise in price significantly, so just accept that your government got there first and you will have to pay through the nose in future.

    By the way, when it becomes abundantly clear that the planet is not going to kill us all in a few years time, please do not be surprised if the politicians of the day claim credit for averting the disaster that was never going to happen anyway.

  30. James McGregor

    Re: Think!

    > what about the Tesla or Think electric car?

    Yes, each produces zero emissions when they're driven. But have a thought as to the power station that generates the power to charge the batteries. A large electricity bill isn't "green" as it has a big CO2 footprint in itself.

  31. Ole Juul

    Make less trips - get a truck

    It seems to me that the list is comprised of toys for people who are too lazy to ride a bike. I can't imagine what someone in the city would need a car for anyway. Around here people tend to drive pickups and larger trucks so they can carry more and make less trips, but then that's country life. Most city folk probably couldn't even get 10 chords of wood in their apartment if they tried.

  32. Anonymous Coward
    Anonymous Coward

    Re: "Green cars" - an oxymoron?

    > Nuclear power stations (for example) don't produce CO2.

    Yes, because extensive strip mining with heavy plant doesn't produce any CO2 does it? Or the extensive processing needed to get it in to usable form, or the re-processing, or the storage of waste (which needs to be cooled), not to mention that a Nuclear power plant uses a lot more CO2 in it's build than other types.

  33. Simon Brown

    how can a car use less fuel but produce more CO2 for the same distance

    How about when one of the cars is fuelled solely by the combustion of long-chain hydrocarbons and the other is electrically propelled?

    Of course these figures don't take into account the vast quantities of CO2 produced by the power stations producing the electricity so in fact it is not a fair comparison.

    As for the argument against biofuels: I think you're right - if we use lots of arable LAND to make fuel we will run out of LAND for producing edible crops, all of the LAND will be making fuel and there will be an unsustainable monoculture thanks to the misuse of LAND for making fuel. I'm sure it would be impossible for anyone to SEA a potential solution... are there not algae that could be grown in the oceans that could produce oil?

  34. Charlie Clark Silver badge

    It's a start

    The UK government has been a notorious stick in the mud when it comes to greening the economy. This website while largely PR will give buyers who are interested at least some idea about the fuel efficiency of a car that they are going to buy anyway. Over time it will probably cover older models in the second hand market and this will have an effect on the market. It won't directly effect emissions themselves and as long as roads are still being built and commuting subsidised things will continue to get worse but you've got to start somewhere.

    Now when are they getting round to enforcing energy passes for houses so that people get a better idea of their future energy costs? The German government has yet again postponed their introduction by over a year until 2009. :-(

  35. Anonymous Coward
    Anonymous Coward

    Inaccurate information on the website?

    Looking at the gov's "Top 10" only website...If you go to the "performance" category, there's some prertty inaccurate information as the tax band G cars are said to have an anual cost of £300. Didn't our new PM raise the cost of the "most polluting" cars earlier in the year to £400?

  36. Luke Wells

    CO2 figures are useful?

    I don't see why CO2 figures are useful?

    Should you not just buy the car in the class you want that has the best mpg?

    What is better :-

    A) A car that does 10mpg, but is soooo ineficient, that it doesn't burn all the fuel properly and thus produces very little CO2

    B) A car that does 50mpg, but burns 100% of the fuel cleanly and produces loads of CO2

    Surely without any doubt the answer is B. Buy the most economical car. The more efficient the car for its class, the less nasty stuff comes out of it over a set distance.

    And what the hell is wrong with CO2 anyway? All the plants in the world need CO2 to live, which then convert it into oxygen for us to breathe, so surely the answer to combat the problem with CO2 (if there is infact a problem with CO2) is to plant more trees instead of cutting them down?

    Global warming does not exist. It has not been proven to exist. Unless you have some scientific facts that the rest of the worlds scientists don't have, please don't try and argue that it does. That is what the "greeny" scaremongers are for. The average temperature of the earth has increased by a minute ammount over the last 1000 years ..... which. is what is going to happen natuarally anyway even if humans did not exist on this planet.

  37. Anonymous Coward
    Anonymous Coward


    What a complete load of Bollocks!

    If you renew your car every, say, five years, you will be causing a new car to be built (with the attendant eco impact) every five years. Your old car (unless you scrapped / recycled it - and I'll bet you didn't 'cos you wanted the residual value back) will still be around being driven by someone else. It doesn't matter that your new one uses less fuel / produces less CO2, the old one's still there.

    The only reason for buying a new, more economical car is to save yourself money on fuel, pick up the Government incentives to buy a new car in reduced tax for newer (read more economical) vehicles and give yourself a nice, self-centered, eco-friendly feeling.

    Go and look at the "dust to dust" energy impacts out there (i.e. over the full life of the vehicle The Prius comes last, somewhere after the Hummer H2!


  38. Anonymous Coward
    Anonymous Coward

    I wonder

    So I replace my car every 7 years

    thats two cars in the lifetime of my trusty old Audi 90 already, so thats two cars to be stripped, recycled/landfilled/whatever. 2 more cars produced to replace it...

    Anyone else see a pattern? Yes, its big and thirsty but its still probobly got a smaller carbon footprint than the 3 cars I'd need in its place. Not to mention I have serious doubts about any new car lasting seven years, 4 years is giving my partners french creation significant issues.

    And for info, dust to dust carbon emission wise, the Prius is about the worst car you can get, with the Cherokee being the best, go figure.

  39. Hamish

    Bloody conspiracy theorists

    If taxing CO2 is like taxing the air we breathe, then stopping people dumping effluent into your rivers is just another way the government controls the water you drink.

    Nothing ever gets proved outright by science, but the probability of global warming at the levels we are seeing being caused by natural cycles is virtually nil. Christ, if you don't understand academic papers it's not as though you can't just go and watch a documentary movie about it.

  40. Chris Bradshaw

    What about...

    ...if we plant more trees ?

    Trees 'breath' CO2 and release O2. Good for everyone isn't it?

  41. Ole Juul

    Quantity is reality - Percentage means nothing

    The thing that governments usually ignore is QUANTITY. We need to stop talking about percentages and start considering just how much actual polution a car produces. No matter how poluting a car is, if you drive it half as far, then it will produce half the pollution. There are many ways to cut down. The largest amount of polution that a car produces is probably in it's production, so in many cases driving an old car is likely less poluting than getting new one, especially if you would get a hybrid.

    When my neighbour goes to town, he drives a little small engine car with minimal pollution. Once a week or so, I hear him fire up the old rust bucket, oil spewing, needs a ring job, truck of his, and I can smell it in my house right away. However, the vehicle cost him nothing, and the way it is used, the fuel consumption (maby 5mpg!) is ACTUALLY very little because he only goes a couple of miles. Now, if that vehichle was taken off the road, he would have to get a new truck in order to do the things he needs like pick up firewood, machinery, etc. He wouldn't be able to afford a small car anymore and his OVERALL polution would skyrocket. The fact is that in many cases, government regulations just increase pollution because all they care about are percentages and not actual quantities.

  42. Erik Hicks

    Consumption vs CO2

    The reason consumption vs. CO2 varies is that diesel fuel contains more (hydro)carbon (and thus more energy) per unit volume compared to petrol. If you burn one litre of petrol you get 2.31 kg CO2, while one litre of diesel gives you 2.68 kg CO2. This is independent of the engine efficiency, which is a measure of how much of the chemical energy stored in the fuel you can extract as power. Higher efficiency = lower consumption for the same work.

    All modern combustion engines burn virtually 100% of the fuel, if not they would never pass emission testing (where would the remaining unburnt fuel go?), so CO2 is directly related to consumption within the same fuel type.

    While low on CO2 emissions, diesels also emit particulates that are allergenic and thought to be carciogenic, as well as NOx that is poisonous and contributes the the lovely brownish-yellow haze above large cities (petrol engines have virtually zero particulate and NOx emissions).

    While particle filters exist (albeit at the price of increasing CO2 through decreased efficiency), a working means of catalyzing NOx is required before a diesel-powered car can be considered as "clean" as a petrol-electric hybrid.

  43. Joel

    Best by far is a hybrid....

    If you look at, you will see that the most fuel efficient car by far is a hybrid - just not a Prius. The Honda Insight gives around 20% than the next most efficient car (although they don't have data on the Polo yet). However, this is no longer on sale.

    The Polo is a small car further cut down to try and get the best fuel efficiency possible. The Insight was also optimised for fuel efficiency, with excellent results. The Prius is designed to minimise the compromises of having a fuel efficient car. The next version of it is expected to give >100mpg.

    The developments they are bringing in seem to be producing major changes in fuel efficiency - a nice change from the previous couple of decades.....

  44. Joel


    There are major issues to consider with the Dust to Dust survey which is currently being used to suggest that the Prius is more energy intensive than a Hummer.

    The initial suggestion seems to go against what I would expect, so I read the report. Amongst the assumptions are that a Prius would only do around 100,000 miles in its lifetime, based upon owners doing 6000 miles per year. In addition, all of the R&D costs were put on the initial model, on the basis that it was possible that the model would fail, and so the investment energy cost has to be bourne by that one model.

    Since there are now version 2 and version 3 coming along, this initial assumption can be shown to be false. Spreading this initial development cost over more vehicles would drastically change the energy requirements of the vehicle. Indeed, if the hybrid technology continues to develop, it is possible that the basic research could move into an entire sector of vehicles, with the cost per vehicle reducing dramatically.

    In addition, there have been dramatic improvements in the technology leading to better fuel performance of >100mpg (

    This is not to criticise the initial report, which was examining the situation at a particular point in time. However the spin being put on it whereby a Hummer is more environmentally friendly than a Prius seems to be similar to the climate change deniers - it is easy to state something, but examining the source evidence can lead to different conclusions.

This topic is closed for new posts.

Biting the hand that feeds IT © 1998–2021