Case Initial Text 1

Do you, or did you, own or lease a Mercedes diesel vehicle in the UK?

You may have been deceived on the price you paid and the level of emissions represented to you and be entitled to compensation.


  • Daimler AG
  • Mercedes-Benz Cars UK Limited
  • Mercedes-Benz Financial Services UK Ltd
  • Robert Bosch GMBH



According to Hagens Berman’s investigations, Mercedes fitted certain of its diesel vehicles with devices to reduce the vehicles’ unlawfully high levels of nitrogen oxide when the vehicles were being tested for emissions. The investigations revealed that during real-world driving conditions, the affected vehicles emitted high levels of nitrogen oxide in excess of what is allowed under environmental legislation. Mercedes' conduct may have led to a decrease in the resale value of its impacted vehicles, as well as increases in environmental pollution.

Indeed, testing at highway speeds, at low temperatures, and at variable speeds, indicated a systemic failure to meet US emissions standards. Low temperature testing at highway speeds for example, produced emissions that were 8.1 to 19.7 times the US highway emissions standard. The US lawsuit argued that testing at low temperatures at variable speeds produced emissions as high as 30.8 times the US standard.  We are investigating the systemic failure of Mercedes vehicles in England and Wales with reason to believe Mercedes engaged in similar behaviour.

Affected vehicles include:

Certain of the following Mercedes models powered by diesel-fueled engines and sold from 2008 up to 2018:  A-Class, B-Class, C-Class, Citan, CLA, CLS, E-Class, GL-Class, GLA-Class, GLC-Class, GLE-Class, GLS, M-Class, S-Class, SLK, Sprinter, V-Class, and Vito (however, additional models are may also have been affected). These models include passenger and commercial vehicles and vans, such as people movers, shuttles and taxis.

How does the Mercedes affected emissions system work?

  • Initial reduction of oxides of nitrogen (NOx) performed by the exhaust gas recirculation (EGR) system.
  • A diesel oxidation catalyst reduces the amounts of carbon monoxide (CO) and hydrocarbons (HC) released from the exhaust and helps keep the particulate trap clean.
  • A particulate filter traps and stores soot particles. The diesel oxidation catalyst upstream helps to remove the particles from the particulate trap, though the engine will occasionally remove excessive particulate buildup by raising the exhaust temperature.
  • In some older model vehicles, a NOx storage catalyst will be used to perform the final removal of NOx from the exhaust before it exits the tailpipe.
  • The vast majority of defeat device-equipped Mercedes make use of a Selective Catalytic Reduction (SCR) catalytic converter (instead of the NOx storage catalyst) to convert the remaining nitrogen oxides to nitrogen and water; so-called diesel exhaust fluid (or “DEF,” a solution of urea and water) is injected into the exhaust gas stream to enable the conversion. In order to prevent vehicles from breaking emissions regulations, the engine may go into a limp-home-mode if the DEF tank is depleted; drivers are instructed to keep the tank refilled as necessary. Some commercial vehicles are equipped with a request or inhibit switch which allows the DEF injection to be "postponed" as it can reduce power output and increase temperatures temporarily; if the vehicle is climbing a grade, for example, it may be necessary to delay the cycle.

In the U.S. we alleged, diesel engines pose a particularly difficult challenge to the environment because they have trade-off between power, fuel efficiency and emissions: the greater the power and fuel efficiency, the dirtier and more harmful the emissions.

“Car manufacturers have struggled to produce diesel engines that have high power and desirable fuel efficiency but also cleaner emissions,” reads the complaint.  “Mercedes’ response to the challenge has been the BlueTEC diesel engine.”

Compared to petrol engines, diesel engines generally produce greater torque, low-end power, better drivability and much higher fuel efficiency.  But these benefits come at the cost of much dirtier and more harmful emissions, including NOx, which include a variety of nitrogen and oxygen chemical compounds that only form at high temperatures.