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.

Fuel accessories and after-market devices include a wide range of additives, devices, systems and services which claim to offer various benefits to vehicle owners including saving fuel, improving performance and reducing emissions.  These products can generally be divided into several broad classes, such as fuel additives, devices placed in contact with the fuel, air intake system, fuel intake system or exhaust system and electronic timing devices.

The ASA has investigated a number of ads for products like this, following complaints challenging whether the efficacy claims could be substantiated.

As with all products, marketers must hold robust documentary evidence to support any objective efficacy claims made (rule 3.7).  The level of evidence needed to support different claims will largely depend on the context in which they appear and how the ASA believes consumers will interpret them. It is a fundamental principle of the Codes that marketing communications must not materially mislead or be likely to do so (rule 3.1).

The ASA has previously ruled that customer testimonials, news articles and papers, certification documents and university theses were not sufficient to demonstrate that a product “saved fuel and increased MPG, prolonged engine life, restored engine performance, reduced emissions, removed carbon deposits from all engine types, prevented wear of engine parts, reduced intermittent acceleration cut-out and engine noise, reduced exhaust fumes, facilitated vehicle inspections for pollution tests (MOT test) or increased engine lifespan”.  They considered these to be objective claims that required robust substantiation based on independent testing and that issues with the test reports, including the age of the testing and the omission of key detail about methodology, meant the ad for an ‘engine carbon cleaning’ product was misleading (Matthew Wallace t/a UK Carbon Cleaning, 4 October 2017).

The claims “Improves fuel combustion which means better MPG and lower CO2 emissions for both petrol and diesel engines”, “Cuts emissions by 30 - 50% and improves MPG” and “makes a positive environmental contribution to a cleaner atmosphere” made for a metal ‘fuel catalyst’ pellet intended to be introduced to the fuel tank or fuel line of a vehicle, were judged to be misleading when the advertiser did not provide sufficiently robust evidence to support them.  The ASA considered that the claims required robust substantiation based on independent testing, and that they needed to see evidence that the results of the tests would be applicable to all or most vehicles. In addition, they considered that any tests and claims based on them should follow, or be of an equivalent standard to, those required by the EU for vehicle emissions.  They did not consider that press releases, customer testimonials and magazine articles were sufficient to demonstrate that the claims had been substantiated (D Lock & Associates t/a Broquet, 27 January 2016).

Similarly the claims "Increases fuel efficiency by up to 25%" and "Reduces engine emissions by up to 80%", for a ‘hydrogen fuel additive system’ intended to be fitted to car engines were ruled against when the advertiser did not satisfy the ASA that their device increased fuel efficiency or reduced engine emissions.  The ASA considered that, as the claims were very broad, the advertiser needed to hold evidence that showed that, under normal driving conditions, all or most vehicles powered by a petrol or diesel engine would achieve a noticeable improvement, with a reasonable proportion achieving the stated maximums, and that any improvement was due to the device (CGON Ltd, 27 September 2017).  Claims from the same advertiser that their products “could cut fuel bills by between 10 and 20%” and help “stop vehicles failing their MOTs on emissions” were also ruled against because their evidence did not convince the ASA there was a good chance that, by using their product, all or most vehicles would obtain a particular increase in fuel efficiency, or that engine emissions would be reduced sufficiently for a vehicle to pass its MOT (CGON Ltd, 9 January 2019).

A website for a ‘hydrogen generator’ stated "reduce CO2 emissions by up to 40% and overall carbon footprint ... Vehicles include: Buses, Trucks, HGVs, Fork Lifts, Transit Vans, Boats, Trains".  The advertiser provided evidence which included laboratory tests involving a bus and some customer trials, however, the laboratory testing did not produce statistically significant results and only involved one type of vehicle and the results of the customer trials were not sufficiently reproducible.  As such, the ASA concluded that the claim had not been substantiated and was misleading (h2gogo Ltd, 26 October 2011).

Similarly claims that a ‘hydrogen performance cell’ “improved vehicle performance, increased fuel efficiency” and helped achieve “lower emissions” alongside more detailed claims connected to specific models were ruled to be misleading as the evidence provided was not sufficiently robust to support such claims (de Verde Ltd, 28 August 2013).

Claims that a ‘HHO gas generator’ allowed to consumers to reduce their fuel consumption and make savings of between 20% 30% in fuel costs were ruled to be misleading due to flaws in the testing and a lack of some essential experimental detail (CED UK Ltd, 7 August 2013).

A social media post stating that a ‘vehicle decarbonising service’ provided "a unique annual/periodic preventative maintenance service, to keep your engine, fuel system and associated components running efficiently by the removal of the harmful build-up of carbon from combustion chambers, turbochargers, catalytic converters and lambda sensors along with removing gums tars and varnishes from your injection system which fuel impurities leave behind” and that they used “a patented, unique, highly refined fuel specifically developed by Canadian Engineers to achieve these objectives on both petrol and Diesel engines”, were judged to be misleading as the evidence provided was not adequate to demonstrate that the product would have a noticeable benefit on engines in most, if not all, types of vehicle, in the ways described (Randstad Ltd, 8 August 2018).

Claims that a ‘car tuning service’ “cut exhaust emissions by 27% compared to comparative products” and “save fuel costs by 12%” were ruled to be misleading because the evidence provided in respect of the product’s ability to reduce fuel emissions across a range of vehicles and by comparison to other car tuner products (representative of those across the market) was insufficient and the document provided in relation to the 12% saving in fuel costs was not sufficiently robust (BVS Ltd, 21 August 2019).

Marketers are best advised to ensure that they hold robust and independent documentary evidence to support any objective claims and that their claims accurately reflect the evidence they hold.  Broader claims are likely to require more comprehensive testing and evidence should usually demonstrate the claimed benefit under normal, real-life driving conditions.

See also, Misleading Advertising, Substantiation.

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