Jaffa’s Green Car Awards 2011

Friday 25th March, 2011
Welcome to Jaffa's Green Car Awards 2011 - which we believe are the first analysis that, with help from our milesperlitre.com,compares cars based on all tailpipe emissions and also includes every car with official published emissions data.

You may have see many so called "green" awards across other websites and magazine, from the greenest 4x4 to the greenest hot hatch. All the winners are chosen from a carefully selected short list and usually result in the winner being a heavy polluting diesel car from a brand that the website appears to have a particular affiliation with and happens to have a fairly low CO2 output along with being a "great car". Rarely are the results explained and it's often pretty impossible to understand why one car is rated higher than the next.

With Jaffa's Green Car Awards 2011, we aim to completely remove subjectivity from the results. The winner in each class won't be the car I like the most, I've probably never driven it, it will simply be the result of applying a mathematical formula to the emissions numbers of every car in the official VCA database. The only real limitation is that the car must be public information in the VCA database that was published in March 2011. There are sadly some notable exceptions from the list, for example emissions data for the Honda CR-Z and Ferrari 458 weren't published at all, but I must only take officially produced data from the government body into account. In some cases, I've noticed variation between the official government figures and those supplied direct from manufacturers so the only fair way of extracting the results was to use all the data from one, trusted, source and simply exclude any vehicle that doesn't appear within.

With the help of the vehicle calculator on milesperlitre.com we've taken not just the CO2 emissions but also factored them in with emissions for NOx, Hydrocarbons, Carbon Monoxide, PM10 Particulates and even noise. Weightings are given to each emission type based on which we believe are most harmful for air pollution. PM10 particulates, a major contributor to pollution and ill health, are weighted heaviest in the results. Hydrocarbons (unburnt fuel) and NOx are weighted equally, both causing similar undesired results when released into our atmosphere. CO has a lower, but still significant, weighting. We add this result to the CO2 and finally throw in the noise simply as a tie-breaker. Essentially, if 2 cars have exactly the same substance emissions, the quietest one will be ranked higher.

Our end result is a "Green Rating" - the lower the number the greener the car. Our cleanest car immediately became apparent and we used this as a benchmark score - expressing all other green ratings as a percentage of this one. So our winner will have a green score of 100% whereas a score with 20% more emissions will have a rating of 80% - this will allow readers to compare one car's score directly with another and rank them appropriately.

The formula generates some interesting results. For example, the Polo 1.2 TDI 75PS BlueMotion, Skoda Fabia 1.2 CR TDI 75PS Greenline II and SEAT Ibiza ST 1.2 CR TDI 75PS Ecomotive are essentially the same car with the same engine. The SEAT, however, has a CO2 output of 92, compared to 89 for the Polo. Arguably, though, the CO2 is higher as it successfully manages to combust its harmful particulate emissions to nil on the Ibiza compared with 0.25 on the VW. End result is that they have the same Green score. By contrast, the Fabia also has the lower 89g CO2 output, like the Polo, and maintains the impressive nil particulate emissions of the Ibiza - sadly, though, it appears to do so by having a slightly less efficient catalytic converter - resulting in lower NOx but higher hydrocarbon and 10 times the Carbon Monoxide emissions. End result, all that poisonous CO reduces its score and it ranks marginally lower than the other two.  I'll post a link to the full results, hosted on milesperlitre.com, a little later.

So, after that inconveniently long but rather necessary introduction, let's move on to our results!

Cleanest Supermini

A fairly easy section to categorise, I went through the list and pulled out those little cars designed for easy parking in town centres. Right at the bottom - let down with high emissions in many areas, especially particulates - comes the Mercedes A Class 180 CDI with automatic transmission, diesel engine, 16" rear wheels - a Green rating of just 38.31%,  lower than a Porsche 911 C2S!

Easy winner, with a Green rating of 89.42%, comes the SMART fortwo coupé 71 bhp mhd with Softip automatic transmission & 15" rear wheels.

Cleanest MPV

Another section with very recognisable members from the school run. I had an idea of what might win this, but was completely wrong. It certainly wasn't the, bottom of this category and one of the dirtiest cars in the UK, Mercedes R 300 CDI with 18", 19", 20" & 21" rear wheels and its Green score of 27.58%.

Instead, the honours go to the Skoda Roomster 1.2 TSI 105PS with 7speed DSG with petrol engine and a Green Rating of 70.64%.

Cleanest 4x4

I originally intended two separate 4x4 categories, one for larger and another for smaller models. However, they both had exactly the same winner.the Lexus RX450h petrol/electric hybrid. With a Green rating of 68.79% it easily appears within the top 100 of all 2700+ vehicles tested, despite its large size and big 3.5l petrol engine.

Compare that to the worst model in this category, the Audi Q7 6.0 V12 TDI quattro 500PS Tiptronic - which manages to be the most polluting vehicle in the UK, coming lower in the list than many Light Commercial Vehicles with a Green rating of 20.31% - almost 5 times the emissions of our cleanest car.

Cleanest Estate

Continuing the trend, another petrol engined winner, the SKODA Fabia Estate.1.2 TSI 105PS with 7speed DSG and a Green rating of 72.53%.

Propping up the rear in this class, with a Green rating of 31.30% is the 2011 Mercedes C-Class Estate C 350 CDI with 18" rear wheels.

Cleanest Crossover

I'll be honest, I don't fully understand this new Crossover sector but it's growing fast. Essentially, we're talking shrunk down SUVs which often only have 2-wheel drive. Worth a mention here is one of the most well known models in this segment, the Nissan Juke 1.6 DiG-T, which manages to be one of only 2 cars in the UK with an NOx rating of just 1g. Sadly, it goes towards proving my catalytic converter theory as the low NOx gives way to massive CO emissions of 444mg and ruining its Green rating which comes to 51.12%.

Instead, cleanest car in this segment goes to the petrol engined Toyota Urban Cruiser 1.33 VVT-i 6 speed Manual with a Green rating of 65.50%. Good, but still amazingly lower than the significantly larger Lexus RX450h that won the 4x4 category.

Cleanest Rep-mobile

Think of cars like the Mondeo, Passat, Accord or, if you're lucky, the 3-series BMW. For those who long to have their boss's company car options.  

Dirtiest car here is the Renault Laguna Coupé V6 dCi 235 FAP and a Green rating of 30.94%.

Opposite end of the scale comes the petrol engined SKODA Superb Estate 1.4 FSI 125PS. Not only somehow cleaner than the hatchback equivalent, but also the cleanest Skoda of all with a Green rating of 60.65%

Cleanest Executive Car

For the Sales Manager, not the rep, think BMW 5 Series and E Class segment. The worst car in this category falls to the diesel fuelled 2010 Infiniti M and a Green score of 30.08%.

Cleanest car by far in this category, appearing cleaner than the Hyundai i30, is the Lexus GS450h on 17" wheels. Single digit NOx and CO that is around a third of that emitted by the Juke, results in a Green Rating of 60.28%.

Cleanest Luxury Car

For those with a millionaire lifestyle come the luxury cars. Think big BMW 7 series, Lexus LS, Merc S Class and other luxury saloons. None of them will even get a mention here. Cars like the Rolls Royce Phantom (25.03%) and Aston Martin Rapide (28.63%) are propping up the bottom of the list but then enters the Porsche Panamera Hybrid Tiptronic which, despite its amazing performance, manages to pull a Green rating of 77.91% out of the bag. Big, fast, luxurious and, somehow, one of the cleanest cars in the UK. NOx, THC and CO are just 12mg combined!

Cleanest Premium Compact

A rapidly growing segment that contains cars like the BMW 1 Series and, dirtiest in the category, Audi Sportback A3 2.0 TDI 170ps quattro with DPF and its Green rating of 36.88%.

For cleanest in the sector, look no further than the Lexus CT200h petrol hybrid which very nearly took the cleanest car award due to emissions like 3mg of NOx, but ended up with a Green rating of 95.90% and fell into a very respectable 2nd place.

Cleanest Convertible

The best top down option, without choking on your own fumes, couldn't be further away from our most polluting convertible - the Maserati Grancabrio (27.23%).  Our cleanest convertible is easily the SMART fortwo cabrio 71 bhp mhd with Softip & 15" rear wheels. With a Green rating of 88.17%, this is easily also one of the cleanest cars in the UK.

Cleanest 2 Seater Sports

No kids and a few quid to spare? This is the category for you. Honours go to the Mazda MX-5 2.0 Petrol and a Green rating of 58.18%, worlds apart from the Aston Martin V12 Vantage (28.49%).

Cleanest 2+2 Sports

Those sporty little cars that have a couple of useless seats in the back, only good for taking the kids to school. Enter our cleanest 2+2, the AUDI TT Coupé 2.0 FSI 211PS with Stop-Start and a Green rating of 58.11% - rather better than the Maserati Granturismo with more than double the emissions at 27.49%.

Cleanest Petrol (non-hybrid) Car

An award for the cleanest petrol driver car on sale that doesn't have a box of batteries in the boot.

This goes to the SMART fortwo coupé 71 bhp mhd with Softip automatic transmission & 15" rear wheels, with a Green rating of 89.42%. A second win for this model and a clear indicator that small and light makes being efficient significantly easier.

Cleanest Diesel Car

If you do a lot of miles and must drive a diesel to save money, which are your cleanest and dirtiest options?

For our dirtiest car, it has to be the "dirtiest car in the UK" Audi Q7 6.0 V12 TDI quattro 500PS Tiptronic that also took took the wooden spoon in the 4x4 category with its 20.31% Green rating. But which is the cleanest diesel? A look down the list brings us to, ironically, another Audi - the Audi A1 1.6 TDI 105PS and a Green ranking of 57.63%

Not only did we have to go past 313 petrol or petrol hybrid cars before we found the first diesel; when we did, it still has a Green ranking of only just above half that of our cleanest car. I think that says a lot really.

In another twist of irony, due to CO2 emissions of 105g/km, our cleanest diesel model does not have exemption from the London Congestion Charge whereas the Audi A3 1.6 TDI 105PS Stop Start and a much lower Green rating of 43.42% somehow qualifies despite having CO emissions almost double that of the smaller A1. A perfect example of why London Congestion Charging rules are failing to meet their objective.

Cleanest Manual Transmission

A lot of modern eco cars are fitted with automatic or CVT gearboxes to allow them to force the driver to change gear early and keep revs low. But what if you want a manual transmission in your eco friendly car?

Well, first tip would be to not buy the Mitsubishi Shogun Warrior SWB with its Green rating of 26.07%. Instead, you should go very small and look at the Toyota iQ 1.0 VVT-i 5 speed Manual with a Green rating of 85.75% and overall the 5th cleanest car in the UK.

Dirtiest Congestion Charge Exempt Car

Whilst many different models, petrol and diesel, qualify for London Congestion Charge Emissions; their emissions vary considerably. Our cleanest car here is the, cleanest premium compact, Lexus CT200h and its Green rating of 95.9% but how much cleaner is it than our dirtiest model that also qualifies?

No surprise, it's a diesel and works out to be the Citroen DS3 1.6HDi 92hp 99g with an awful Green rating of just 37.16% - it may be CC exempt but it's CO and particulates are very high. If ever there was a car that proved CO2 shouldn't be used as a measure for CC exemption, it's this one.

Dirtiest "Green" Car

The world's attraction to all things eco has brought upon a tremendous amount of so called green marketing and new model names containing "green" "blue" or "eco". But which car, sold under one of these flogged to death marketing campaigns, has the most overall emissions?

Congratulations to the Volvo XC60 D3 FWD DRIVe Manual which, despite being heavily pushed under their Emissions Equality campaign, only manages a Green rating of 36.04% due to high CO, NOx etc. Thankfully, it fails to achieve congestion charge exemption.

Cleanest Car 2011

So that brings us to our uber-prize. The cleanest car on sale in the UK and the one we used as a benchmark for all the others to follow. It didn't just win cleanest car, we had to skip some other awards along the way so as not to announce the winner prematurely.

This car wins the awards for:
Cleanest Car 2011

Cleanest Hybrid

Cleanest Automatic Transmission

Cleanest Compact Family Car.

But which was our winner? I bet you guessed wrong!

Winner of Cleanest Car 2011, cleaning up with 4 different Green awards is the amazingly clean Honda Insight 1.3 IMA S 5 door which, by definition, takes a 100% Green rating.

Despite all this, however, it fails to qualify for exemption from the London Congestion Charge as it has a CO2 rating of 101g/km. There's something truly wrong in the world when a car as clean as this fails to qualify.

In fact, across all our 21 categories, just 3 of our true winners, the Lexus CT, Toyota iQ and Smart fortwo actually qualify for London CC exemption. It's time we lost some of our focus on CO2, left our obsession with "clean diesel" behind and focussed back on clean petrol and petrol hybrid cars. Over 300 unique models are cleaner than any diesel vehicles on the road.

Top 10 Cleanest Cars

1) Honda Insight - Petrol Hybrid (100%)

2) Lexus CT200h - Petrol Hybrid (95.90%) *

3) Toyota Auris Hybrid - Petrol Hybrid (93.41%) *

4) SMART fortwo - Petrol (89.42%) *

5) Toyota iQ - Petrol (85.75%) *

6) Nissan Micra - Petrol (81.39%)

7) Nissan Pixo - Petrol (79.09%)

8) Suzuki Alto - Petrol (79.09%)

9) Toyota Prius - Petrol hybrid (77.97%) *

10) Porsche Panamera Hybrid Tiptronic - petrol hybrid (77.91%)

* denotes congestion charge exemption

You can view Green rankings, running costs and emissions data by visiting:


  1. 1) John C. Briggs Said: (25/03/2011 13:44:57 GMT) Gravatar Image
    Jaffa’s Green Car Awards 2011

    OK, so the Prius has 10% lower C02 and NOx than the Honda Insight, yet the Honda Insight wins? Why? It seems to be that the author heavily weights THC and CO output, for which the Insight appears to be dramatically and suspiciously lower?

  2. 2) John C. Briggs Said: (25/03/2011 13:46:30 GMT) Gravatar Image
    Jaffa’s Green Car Awards 2011

    And why are we comparing a MY2011 Lexus CT200H with a MY2009 Prius considering that the Prius was extensively redesigned in 2010.

  3. 3) Ben Rose Said: (25/03/2011 14:18:43 GMT) Gravatar Image
    Jaffa’s Green Car Awards 2011

    @1 John,

    OK, you're comparing the Honda Insight { Link } with the Toyota Prius { Link }

    The Insight has CO2 of 101g/km, the Prius has 89g/km. The Prius is indeed lower but, in terms of air quality and human health, CO2 has never been proven to be a factor at all. It might, big might, contribute to global warming but this is just a theory. Nevertheless, the CO2 measures for both cars were factored into the Green Ratings for both scores.

    NOx different are just 1g/km different - 6 for the Prius and 7 for the Insight. Hardly anything to choose between them. Both are excellent results, but a marginal win for the Toyota in this category.

    Finally, we'll look at the Carbon Monoxide (CO). The Insight emits just 50mg/km of CO, compared with 258mg/km for the Prius - that an 81% margin of difference.

    Unlike the CO2, which was only a 12% margin and doesn't affect human health, CO reduces the blood's oxygen carrying capacity and which can reduce availability of oxygen to key organs.

    If carbon monoxide has leaks from a gas appliance in your home, you may well die in your sleep.

    If you run a hose from your tailpipe into the passenger compartment of your car, it's the carbon monoxide that kills you first. Arguably, a hose from a Prius may kill you 5 times quicker in that scenario - except you'd struggle to get any emissions out of either car when stationary!

    In terms of air quality, in my eyes, CO is critical and the Prius emissions are relatively high. If you compare to Auris hybrid and Lexus CT, which carry pretty much the same powertrain, you'll see CO from those vehicles is much lower - hence their higher ratings than the Prius.

    Honda have proved you can build a car like this whilst maintaining a low emission of CO - they paid for it in their CO2 rating - fully oxidising all of the carbon emissions will indeed contribute to that.

    Take a look at the linked figures - by comparison, the Prius emits a considerable amount of uncombusted Hydrocarbons from it's exhaust 58mg/km for the Prius vs. just 23mg/km for the Insight. This is another thing that heavily weighs again the Prius - THCs contribute to low level ozone (producing smog), are indirect greenhouse gases and can also be carcinogenic (cancer causing).

    Given a choice of 3 rooms, one containing CO2 pollution, one containing CO and one containing THCs, which would you choose to sit in?

    I trust that explains the result in a little more detail.

    To answer your 2nd query, these car are UK models. What you would know in Boston to be the 2010 Prius is actually a 2009 model here in the UK. These are the stats for the latest Prius in the UK.

  4. 4) AndyElvers Said: (25/03/2011 14:53:08 GMT) Gravatar Image
    Jaffa’s Green Car Awards 2011


    I agree the figures for the G3 Prius do look a little odd considering the Auris and CT200h use essentially the same drive train.

    Now the emissions data for plug-ins is a whole different topic. Quoting one figure just doesn't cut it IMHO as the recent press releases on VW's "300mpg" diesel and the Porsche 918 show. A discussion for another blog I would have thought.

  5. 5) Alex Willmer Said: (25/03/2011 15:27:20 GMT) Gravatar Image
    Jaffa’s Green Car Awards 2011

    Ben, I won't comment on the particular scores, but I'd like to know the full details of how you reached them. What formula/algorithm you used? What values/weightings did you use?

    I ask because rankings such as this a highly sensitive to these, and minor changes can greatly affect the outcome. If they aren't published, then the validity of the ranking can't be verified. Thus the ranking isn't useful.

    In answer to your last question: "Given a choice of 3 rooms, one containing CO2 pollution, one containing CO and one containing THCs, which would you choose to sit in?" I wouldn't choose any of them without knowing the levels of each gas, and the toxicity of each at that level. It's no good saying CO2 is worse than CO, or PP10 is worse than NOx. What matters is: How much worse? Does a million cars at 258mg vs a million at 50mg result in 5x more deaths? The precise details of how you ranked these cars matters, without knowing it nobody can say whether your ranking means anything.

    P.S. Good point about the ineffectiveness of using a stationary hybrid/stop-start car for suicide. Hadn't thought of that :)

  6. 6) Ben Rose Said: (25/03/2011 16:03:52 GMT) Gravatar Image
    Jaffa’s Green Car Awards 2011


    I'm totally with you and I know, in your shoes, I'd likely be asking exactly the same.

    My aim was to do a quick analysis of all the cars, work out which ones were the best and then publish all the results and the working out.

    I ran the data by a few people, who truly didn't understand it, and realised that it was pretty useless for my target market - so I converted it all to the percentage form you see above.

    Ultimately, my quick study didn't take a few hours like I intended. It worked out more like many days of number crunching and analysis. It made me realise why "green car guides" aren't based on these numbers - they are extremely complex.

    I studied so called "safe limits" for each emission type in the UK and other countries. I studied the effect of each one. I studied their chemical composition, for example 1mg of particulates will contain more than twice the amount of carbon found in 1mg of CO and and less than a third that found in 1mg of CO2.

    I worked the numbers over and over and came up with a formula that I felt best reflected the scenario and fairly equated the different emission types. I wanted to be in a position such that, when people like John C. Briggs came along, I could give them a fact based response and explain why any Car A ended up rated higher than any Car B.

    Unfortunately, the only way I can protect the time and intellectual property I've put into this, is to not publish the exact formula. This way, my idea cannot be stolen and I maintain the value of my results for when I perform an updated survey in the future.

    I accept, to people like yourself, this may leave the results open to question - I accept that. I'm more than happy to answer queries such as those from Mike, should any more arise, if anybody feels that the results don't accurately reflect the emissions balance of any particular model of car. I've spent a considerable amount of time to avoid such a scenario.

    Ultimately, you can choose to accept my Green ranking or ignore it. Either way, there's an excellent comparative table of emissions on milesperlitre.com and you can sort them by each emission type as required, or click through to easily see all the emissions data for each car. If you don't like my rankings, you can take the data and create your own. Either way I believe it's one of the best car emissions resources in the world and will hopefully raise awareness of alternate emissions to those blinded by CO2 as the enemy.

  7. 7) Alex Willmer Said: (27/03/2011 18:46:13 GMT) Gravatar Image
    Jaffa’s Green Car Awards 2011


    You stated "we aim to completely remove subjectivity from the results" but you choices for the formula are exactly that - subjective. The only objective statement we can make about your ranking is "Ben Rose thinks it is right" and as you aren't an expert in the field I think there's a high probability your ranking has errors.

    What I'm trying to get across is the nature of the scientific method and why you need to follow it if you want to create a _useful_ ranking that others can trust. I understand your reluctance having put in so much effort, and I appreciate the data you compiled from VCA - it looks very useful. However publishing a conclusion (your ranking) without the accompanying methodology (your formula with justifications) by which others could verify or falsify your work is worse than wrong.

    Best wishes, Alex

    P.S Sorry for the delay in my reply. If you'd prefer to discuss this privately, my email is alex@moreati.org.uk

  8. 8) Ben Rose Said: (27/03/2011 20:10:08 GMT) Gravatar Image
    Jaffa’s Green Car Awards 2011


    Appreciate your perspective, glad the compilation of data may be of use.



  9. 9) Mark in California Said: (06/08/2011 02:13:53 GMT) Gravatar Image
    Jaffa’s Green Car Awards 2011

    Thank you! It's so good to finally see someone acknowledge that there's way too much emphasis on CO2 emissions and not enough attention given to "real" pollution that we breath every day. And I also agree with you that "clean diesel" is an oxymoron.

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