The premium brand from Stuttgart was among a list of suspects in the aftermath of the Dieselgate scandal (pretty much every European car maker that claimed to sell "clean diesel engines" was targeted), but it has always defended its diesel engines saying they comply with every existing rule and that they don't use any defeat devices.Well, this resolute position that Mercedes-Benz has taken will be tested once again shortly, as the Environmental Protection Agency has requested explanations over the emission levels of some of the company's diesel engines. EPA insisted it hasn't started an official investigation, but is simply asking Daimler for further information on the subject.The enquiry came as a result of a class-action lawsuit launched on February 18, 2016, by law firm Hagens Berman in the New Jersey District Court. In this lawsuit, Mercedes-Benz is accused of misrepresenting the performances of its BlueTEC-badged models, which it claimed was "the world's cleanest and most advanced diesel."The allegations made by Hagens Berman are as serious as they come, and should Mercedes-Benz be proved guilty, it could face a somewhat similar backlash to that experienced by Volkswagen. However, a Daimler spokesman has branded the allegations as completely bogus and said the company would work together with EPA to prove its innocence.Daimler is accused of knowingly programming its BlueTEC models to emit very high levels of nitrous oxides (NOx) while operating at temperatures below 50 degrees Fahrenheit (10 degrees Celsius), reaching levels over 65 times the maximum quantities allowed by EPA. Automotive News reports that Daimler defended itself by saying that all of its cars play by the rules, but it did concede that under certain conditions, a system that treats exhaust fumes could operate at a reduced capacity to prevent condensation, which could generate corrosion and damage the integrity of the engine and exhaust system. However, Daimler says that this feature is perfectly legal (and given that they publicly admitted to its existence, we'd tend to believe them).Since Daimler promised its full cooperation, EPA should be able to come with a verdict soon, so waiting for the lawsuit to end might not actually be necessary, as the Agency's findings should be conclusive enough. We'll probably be hearing more on the subject in the following days.