Note: This advice is given by the CAP Executive about non-broadcast advertising. It does not constitute legal advice. It does not bind CAP, CAP advisory panels or the Advertising Standards Authority.

Vehicle emissions, fuel consumption and climate change have been at the forefront of press, public and government agendas. Marketers have recognised that many consumers are keen to choose cars that emit less CO2 and other emissions and have chosen to advertise their models with a focus on low fuel consumption.

As a result of a European directive, all ads for new cars must contain information about their fuel consumption and CO2 output. The regulations are monitored in the UK by the Vehicle Certification Agency (VCA), an executive agency of the Department for Transport. Guidance notes on the regulations can be found at

The inclusion of that information does not mean, however, that marketers may exaggerate the fuel efficiency of their cars. Marketers should take care when making comparisons about fuel performance and emissions. They should ensure that it is obvious whether they are comparing the fuel performance and emissions of their car against those of all cars on sale or merely cars with similar performance or in the same category.

The ASA considered that the headline “HIGH PERFORMANCE. LOW EMISSIONS. ZERO GUILT” implied the advertised car had low emissions compared with all cars, not merely similar ones. Even though the body copy of the ad had stated “category-leading low CO2 emissions” and the consumption figures had been stated in a footnote, the ASA nevertheless considered the ad was misleading (Lexus (GB) Ltd, 23 May 2007).

Similarly, the ASA considered that the claims "ultra low 142 CO2 g/km" and "Low emissions" implied that the cars shown had low emissions compared with all cars. It concluded that the claims were misleading even though both cars produced a lower level of emissions than other cars with a similar performance (Citroen UK Ltd, 8 August 2007, and Volkswagen Group UK Ltd, 20 December 2006). The ASA also considered that the claim "CO2 emissions for the range are down to 139g/km which means it’s better for the environment", misleadingly implied that CO2 emissions were low for the whole range rather than just for two of the models within it (Mercedes-Benz, 30 September 2009). A similar complaint regarding emissions claims that were not supported for the whole range was also upheld (Volkswagen Group UK Ltd, 22 April 2009).

Another ad, which contained the image of leaves coming out of a car exhaust and claimed “eco2” and "eco-logical", was found to have exaggerated the environmental benefits of the advertised car because it implied the car did relatively little harm to the environment and had low emissions compared with other similar cars (Renault UK, 26 March 2008).

Ads for fuel efficiency devices are also problematic if the efficiency claims made are not supported by rigorous testing. If claims are made in relation to CO2 reduction, increased mileage or the like the advertiser must ensure that they can be adequately substantiated (Ecotek Technologies plc, 30 June 2010; h2gogoLtd, 26 October 2011).

The lesson in all of the above cases is that marketers should not exaggerate the environmental credentials of their products, they should ensure the basis of their claims and their comparisons are clear and they should hold evidence for the claims that they make.

Conversely, the ASA accepted the claim "ONE DAY ALL CARS WILL BE THIS GREEN" because the advertiser showed that the car was one of the greenest cars available because it was among the 15% of cars with the lowest CO2 emissions (Daihatsu Vehicle Distributors Ltd, 26 May 2004).

Advertisers should ensure that claims comparing the emissions of their cars with those of other cars in the same tax band do not mislead consumers. The ASA considered that readers would understand the claim “With only 120g CO2 per kilometre, it's the lowest in its class" to refer to a comparison with all cars in the "small family" car class, not only those with automatic gearboxes and diesel engines. (Citroen UK Ltd, 31 October 2007). Another advertiser was unable to provide substantiation for the claim "lowest emissions in its class" (Colt Car Company Ltd t/a Mitsubishi Motors, 12 September 2007).

Marketers should ensure that advertisements that feature more than one car do not imply that all the cars in the ad have low CO2 emissions if they do not. (Suzuki GB plc, 16 January 2008, and Fiat Group Automobiles UK Ltd, 25 June 2008).

CAP advises marketers making environmental claims to be specific, not general, in their claims to avoid the risk of confusion. For example, the ASA considered that the claim “The environmentally friendly 607 HDi diesel" implied that the car caused no environmental damage, an implication that the advertiser could not substantiate (Peugeot Motor Company plc, 18 September 2002). The ASA noted the 607 HDi diesel was in the (then) lowest taxation band for company cars but considered that that did not make it environmentally friendly. The ASA concluded that, by not supplying evidence that the car caused no environmental damage, the advertiser had not justified the claim.

Similarly, the ASA considered the claim “designed with ... the utmost respect for the environment in mind" was misleading because the petrol model of the car shown was rated in band E and the diesel model in band F of the vehicle excise duty rankings for emissions. (Johnsons Cars Ltd, 1 August 2007).

More specific claims, such as "FROM THE GREEN 4x4 RANGE OF THE YEAR" and "Winner Green 4x4 range of the Year" are unlikely to breach the Code if the marketer holds evidence to support them. (Daimler Chrysler UK Ltd, 2 July 08)

In September 2008, the ASA upheld complaints about an ad, for a hybrid, that claimed “Perfect for today’s climate. (And tomorrow’s)” and “Driving the world’s first luxury hybrid SUV makes environmental and economic sense”. The ASA concluded that the ad exaggerated the vehicle’s green credentials by implying its emission rate was low, regardless of the category of car and that the car caused little or no harm to the environment (Lexus (GB) Ltd, 24 September 2008).

Marketers of electric vehicles should take care not to exaggerate their products environmental credentials, for example by making unqualified claims about CO2 emissions. The ASA recently considered complaints regarding the Nissan LEAF electric car. The complainant objected to the claim "Zero emission by Nissan" on the basis that this claim was only true of the car whilst it was driving. The ASA considered that the claim was made in the context of a website and downloadable brochure that further explained that "The all-electric Nissan LEAF doesn't produce one gram of CO2 whilst driving" and therefore considered that the basis for the claim had been suitably explained.

Marketers should bear in mind that in a different context, without sufficient explanatory text, the claim may have been considered misleading. (Nissan Motor (GB) Ltd, 22 February 2012).

Marketers should also be wary of making implied environmental claims by exaggerating the likely MPG that can be achieved by a vehicle (The Colt Car Company Ltd t/a Mitsubishi Motors UK, 13 August 2014).

See other entries on ‘Environment’.


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