Emissions cheating allegations are now being levelled against all car manufacturers who sold diesel vehicles in the UK between 2009 and 2018, by London law firm Harcus Parker.

Businesses, company car drivers and the rental and leasing industry could be eligible for compensation if the claims are successful.

Following the dieselgate scandal, Volkswagen Group was the first brand to face civil action with some 90,000 UK owners seeking compensation. The carmaker, however, is defending the claim and says that claimants did not suffer any loss. The case is ongoing.

Class action lawsuits have since been launched against Daimler, Fiat Chrysler Automobiles, Renault, Nissan and Vauxhall by numerous firms in the UK and Harcus Parker plans to begin legal proceedings against all other manufacturers of diesel vehicles in the coming weeks. The cases are expected to last for around two years.

All the car brands involved in existing claims deny the allegations.

Damon Parker, partner at Harcus Parker, said: “My clients bought diesel vehicles after believing the messages pushed on them from all sides that ‘clean diesels’ offered a win-win solution to the problem of increasing CO2 emissions.

“Unfortunately, this ignores the difficulties manufacturers have always faced in controlling emissions of nitrogen oxide (NOx). The effects of diesel fumes on air quality is now becoming more well known, and my clients hope that by holding vehicle manufacturers to account for breaching regulatory limits, they can help to protect the environment, air quality and our health in the future.”

Car manufacturers are accused of using illegal defeat devices to manipulate the emissions performance of vehicles at certain times, such as during emissions tests, to make their cars appear to be more environmentally friendly.

All vehicles registered between 2009 and 2018 underwent the New European Driving Cycle (NEDC) test, in order to gain type approval. While EU law bans the use of ‘defeat devices’, exceptions within the regulations allow the effectiveness of emissions control systems to be reduced if it’s required to protect the engine against damage or ensure its safe operation.

Nick Molden, founder and CEO of independent vehicle emissions testing firm Emissions Analytics, told Fleet News: “The regulations set a NOx limit in ‘normal driving’ but, in Europe, there was no description of what normal driving was – only the official NEDC cycle, which varied totally from normal driving.

“Manufacturers have worked through the regulations and found what specific tests they had to meet. No carmaker has failed to meet what they had to do under NEDC, but the lawyers argue that they should always meet that.”

A 2016 investigation by the Vehicle Certification Agency, on behalf of the Department for Transport, found that only Volkswagen Group vehicles featured defeat devices designed specifically to beat official testing.

However, the tests provided further evidence that NOx emissions from diesel vehicles were higher in real-world conditions and on the test track than in laboratory conditions.

The investigation concluded that the EU regulations provided uncertainty about how emissions control systems may be reduced or deactivated in certain conditions and did not detail how the exceptions to the ban on defeat devices should apply, whether or how manufacturers should apply these exemptions, or how a type approval authority should evaluate the validity of their use.

Parker said: “For a vehicle to perform significantly differently below 20oC, 17oC or even 15oC is simply unacceptable and in our view is a transparent attempt to manufacture vehicles which purport to pass the relevant tests but which perform very differently in the real world. After all, the average temperate in the UK is around 9oC.”

The excess diesel emissions issue is estimated to affect around 40 million cars in Europe and around 11 million in the UK, including non-RDE Euro 6 models.

The Association of Fleet Professionals (AFP) said it is not aware that any of its members are engaging with class action suits and believes fleet operators are unlikely to seek compensation unless residual values were affected.

Molden said the weakness in class action suits is in establishing that car owners have suffered a loss.

“The consequence of higher NOx is better fuel economy and lower CO2. Consumers have been benefiting – there is no financial loss there. Secondhand car values are also still very strong. People like the fuel efficiency of a diesel vehicle,” he explained.