Hot air: the worst cars for real-world CO2 emissions

PorscheSince the Volkswagen emissions scandal, the spotlight has been focused on the real world emissions of cars, rather than those produced in a lab. As Volkswagen proved, you can post exceptional results under test conditions, only for the reality to be very different indeed.

One organisation is taking a lead. Vehicle testing firm Emissions Analytics is checking the tailpipe emissions of every new car on sale, under its EQUA initiative. It’s already published data for NOx and carbon monoxide: now, it has released the findings of its latest tests for CO2 emissions – which shows car brands overall are missing their target by a whopping 39%. And some are worse still…

The British company’s number-crunching has created two figures: an indication the actual real-world CO2 for all cars on sale, plus a ‘variance factor’ that reveals by how much the real world varies from the official figure. Call this an ‘honesty rating’: 1 is most honest, 5 is least honest.

All new cars are sold with a quoted CO2 figure, which is used to calculate road tax and company car tax. But as Emissions Analytics shows, the cars of certain brands are performing far worse in reality than the figure suggest…

The car manufacturers with the highest real-world CO2

Emissions Analytics

First, to the car brands that produce the most CO2 in the real world, as opposed to a sterile and fully-controlled test bench. These makes of car are, simply put, the very biggest emitters of CO2. They’re the global warming anti-heroes.

10: Audi – 191g/km


Surprisingly, for all its TDI diesel engines and e-tron plug-in hybrids, it’s Audi that has the 10th highest real-world CO2 figure. Blame all those big Q5s and Q7s, plus the R8 supercar? Well, yes, but also blame an EQUA variance factor ‘honesty rating’ of 2.7 over what its official NEDC figures state and how the cars perform in real life. Remember, 1 is most honest and 5 is least honest.

9: Jeep – 200g/km


Jeep is an SUV manufacturer. It makes big, thirsty 4x4s. So it’s perhaps no surprise to see it appear in the CO2 emissions bad books. It’s not all bad news though: when Jeep says it’s bad in official figures, the real-world figures at least prove it’s being honest – its variance factor is just 1.1, compared to Audi’s 2.7.

8: SsangYong – 206g/km


Nearly all of SsangYong’s cars are big, too: the smallest car it makes is the Nissan Qashqai-rivalling Tivoli. Jeep’s are generally bigger though, and both its overall CO2 figure and the real-world variance over claims are better than SsangYong’s…

7: Jaguar – 207g/km


Jaguar’s cars are sporty and premium. The XE has yet to have a big impact on the range, so its overall brand CO2 is driven up by the XF, the F-Type, the XJ. CO2 emissions that vary by 2.5 times over official figures aren’t so clever either, though.

6: Lexus – 211g/km


Jaguar produces less CO2 than Lexus? Hang on a minute, surely that’s not right – Lexus is the brand of the hybrid, after all? Well, yes, but it’s also a brand that sells a lot of RX SUVs. A lower variance factor of 1.9 isn’t enough to offset that – oh, and the fact it doesn’t sell CO2-cutting diesels, either.

5: Infiniti – 213g/km


This is a poor result for Infiniti. According to Emissions Analytics, its quoted CO2 figures underplay the real-world CO2 of its cars by an ‘honesty factor’ of 3.6. The everyday CO2 of its cars is a stonking 213g/km, meaning it puts out more carbon dioxide as a brand than 4×4 specialist Jeep. We thought this brand was meant to be the smart-thinker’s alternative?

4: Subaru – 214g/km


Subaru’s turbo boxer engines sound good in the real world, but you’re best listening to them from a safe distance: their actual CO2 emissions are much higher than the claimed figures.

3: Land Rover – 223g/km

Land Rover

Like Jeep, Land Rover only makes SUVs. Big, posh, heavy SUVs, like the Range Rover and Discovery. The Evoque has helped bring down its range-average CO2 figures, but a variance factor of 2.6 pushes it back up again: bronze medal in the list of manufacturers with the highest real-world CO2.

2: Porsche – 240g/km


Porsche’s sports cars are naturally rather thirsty, and so naturally put out a lot of CO2. Even the slowest, cheapest 911 does 0-62mph in 4.6 seconds – you don’t get such performance without using a bit more fuel than average. Its range CO2 figures are pushed up further in the real world due to a variance factor of 2.0 over what it claims, too.

1: Aston Martin – 314g/km

Aston Martin

It’s perhaps no surprise to find a supercar manufacturer tops the list of the brands with the highest real-world CO2. Aston Martin’s cars all have V8s and V12s, after all. What’s positive for the brand is that its variance factor is a mere 1.0 – it says it’s bad, but it’s very honest when it says this, too.

And now it’s onto the brands whose CO2 figures mysteriously show the biggest variance in the real world compared to what they can achieve in the lab – this is precisely what let Volkswagen down…

The car manufacturers with the biggest real-world variance to official CO2 figures


Car manufacturers blame the flawed NEDC test. Campaign groups say there’s something fishy going on. Experts say brands have simply learnt how to best perfect cars to do well in the very-limited-scope official emissions test, without resorting to cheating.

Whatever the reason, there’s no denying the real-world results are often very different to what’s officially claimed in the legislated CO2 figures. And here are the worst offenders – the brands with the worst ‘honesty ratings’.

Chrysler – 3.1 times variance factor


American brand Chrysler benefits from being part of Fiat, which includes sharing Fiat engines. Which, according to Emissions Analytics, aren’t quite as green in real life as the test figures claim. Another reason for the brand being withdrawn from the UK?

Peugeot – 3.1 times variance factor


Peugeot’s real-world CO2 figures also vary over claimed statistics by a hefty factor of 3.1. And this, from a brand that’s committed to releasing real-world economy statistics for its cars. How long before customers force it to cut down this yawning variance?

Renault – 3.1 times variance factor


Renault’s HQ was raided by investigators looking into evidence of emissions test skulduggery. We’ve heard nothing since so clearly there’s nothing to report – but news of a real-world variance factor of 3.1 over claimed figures should still provide food for thought.

Volvo – 3.2 times variance factor


Volvo prides itself on being a safe, upstanding brand, and part of this sensible-shoes image is serving up great MPG and low CO2 figures. This image takes a bit of a dent, though, as Emissions Analytics finds an honesty rating of 3.2 over what it says and what real-world figures say.

Fiat – 3.4 times variance factor


Fiat’s range is dominated by small cars such as the 500 and Panda, models that will be bought to use mainly in city centres and to save fuel. Pity, then, the honesty rating of 3.4 suggests the real-world CO2 is not very likely to come close to what the official figures say…

Ford – 3.4 times variance factor


This is a significant result, because Ford is Britain’s best-selling car brand. According to Emissions Analytics, its CO2 figures have a variance factor ‘honesty rating’ of 3.4 compared to the official claimed NEDC figures, indicating that in the real world, its cars are not very likely to get close to the official stats.

Infiniti – 3.6 times variance factor


Remember, Infiniti emits one of the highest amounts of CO2: a variance factor of 3.6 suggests it’s less honest in the real world than the figures say it is. It’s not an enviable position for the premium challenger to be.

Alfa Romeo – 3.6 times variance factor

Alfa Romeo

Alfa joins Infiniti on the third-place spot in the honesty rating league table. The firm has to date sold just two cars, the Giulietta and the Mito: will the arrival of the fancy new Giulia help improve matters for the sporty Italian brand? It’s also significant in being the third Fiat Auto brand in the bottom 10…

DS – 4.7 times variance factor


The second-worst car brand for real-world CO2 diverging from the official figures is posh Citroen sister company DS. As Citroen itself isn’t among the bottom 10 (indeed, the C3 diesel is the only car to achieve the best-possible A1 rating), we’re not quite sure why this is so – perhaps the diesel-hybrid DS 5 is having an effect? Whatever the cause, it’s worth bearing in mind if you’re buying a DS with low CO2 in mind.

Smart – 5.0 times variance factor


The least honest brand for real-world CO2 figures? Surprisingly, it’s Smart – makers of the urban-hero Fortwo city car. Smart’s real-world CO2 is the furthest from the official rating of any manufacturer on sale, by the maximum-possible variance factor ‘honesty rating’ of 5.0, which means its real-world fuel economy is likely to be least like the glowing official stats as well. You may think you’re doing your bit for global warming by choosing a Smart, but the planet in reality might not thank you.

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