[:en]Diesel engines are the device which keeps our trucks, passenger cars and trains alive and gives them the power that they need to move. Diesel works more or less in the same way as the gasoline, but they generate more power by working in a subtly different way. One of the most difficult aspects of dealing with Dieselgate is knowing the “language of engines” in order to entirely understand and have a full idea of the issue. Only when one knows  a problem can they speak on it and try to find a solution.

Diesel engines are now part of our existence, but how well do we know them? We will explain in this section how diesel engines work, in which they differ from the gasoline ones and the reason why they became so popular.

Before getting into what diesel engines are it’s important to define a defeat device. This is usually linked to something negative or something that has been abused. They are the system that some car manufacturers, Volkswagen for example admitted to using after the Dieselgate scandal to cheat on emissions’ test so that the emissions would score lower than they actually were.

We also had a closer look at the technologies that have been developed to reduce emissions and to keep them within legal standards. We tried to understand how to justify the high conformity factor since the new technologies are already available for car manufacturers and they can use them.

In this section we will clarify some of the technical aspects behind Dieselgate scandal. Considering that we are not engineers, we turned to experts and scientists in order to have a complete understanding of these aspects.

We will take a look into the future: which are the alternatively powered vehicles that are developing?

Let’s take a closer look!



Diesel and gasoline engines work roughly the same way. Like a gasoline engine a diesel engine is a type of internal combustion engine. It’s the same system consisting of a piston which, moving up and down, compresses the air and expands exhaust gas.

What is then the main difference? As Giovanni Cipolla, who has held different positions in the Fiat Group, explained us, the difference is how the fuel is injected.

In a diesel engine, fuel is injected into a cylinder, combustion chamber, after the piston compresses the air. It is sprayed with droplets that evaporate and burn generating heat.

In a gasoline engine, fuel and air are injected together into the cylinder. The piston compresses the mixture and when the pressure is at the maximum level (the piston is at the top of the cylinder) a small electric spark from a sparking plug sets fire to it. That makes the mixture explode, generating power that pushes the piston down the cylinder and (through the crankshaft and gears) turns the wheels. While in a diesel engine the fire starts in each droplet and so there are millions of points where the fire starts burning, in a gasoline engine, instead, the flame ignites where there is the spark plug and then it spreads.

So in a diesel engine, combustion is faster than in a gasoline one where the flame has to spread. This is the first reason why a diesel engine is more efficient than a gasoline one.

The second concerning reason is the Engine Pressure Ratio, which is higher in a diesel engine than in a gasoline one. A diesel engine can tolerate a higher Engine Pressure Ratio because it compresses just air and the fuel is injected at the end. In a gasoline engine, as we have already said, fuel is compressed with air and the high level of pressure makes the mixture explode itself but in an uncontrolled way.  This is called the “knock” or “detonation”.



The defeat device is a strategy. It aims to arrest the emission control system. If we want to provide a definition of “defeat device”, we can say that a defeat device is any motor vehicle hardware, software, or design that interferes with or disables emissions controls under real world driving conditions, even if the vehicle passes formal emissions testing.

How does it work? The software senses when the car is being tested and then activates equipment that reduces emissions. But the software turns the equipment down during regular driving, increasing emissions far above legal limits, most likely to save fuel or to improve the car’s torque and acceleration. The software is modified to adjust components such as catalytic converters or valves used to recycle some of the exhaust gasses. The components are meant to reduce emissions of nitrogen oxide, a pollutant that can cause emphysema, bronchitis and other respiratory diseases.

It is the Regulation of 2007 (Art.3 par. 10) that defines “defeat device” as “any element of design which senses temperature, vehicle speed, engine speed (RPM), transmission gear, manifold vacuum or any other parameter for the purpose of activating, modulating, delaying or deactivating the operation of any part of the emission control system, that reduces the effectiveness of the emission control system under conditions which may reasonably be expected to be encountered in normal vehicle operation and use”.

An EU regulation is a legal act to which citizenship should be very careful, mainly because it is directly applicable in all Member States and to all EU citizens. It’s just in relation to the text of the law that was played the match between legal and illegal.

 The Regulation in fact, on one hand, prohibits the use of defeat device; on the other, it provides for derogation’s in three specific cases (Art. 5 Par. 2). The prohibition shall not apply in three cases: if the need for the device is justified in terms of protecting the engine against damage or accident and for safe operation of the vehicle, if the device does not work beyond the requirements of engine starting, if the conditions are substantially included in the test procedures for verifying evaporative emissions and average tailpipe emissions.

According to parliamentary inquiry reports published on  December 2016, the presence of these derogation’s has made it possible the alternative interpretations about the defeat device identification and the eventual application of the ban. This leaves room for the possibility of interpretation nuanced the boundaries between lawful and unlawful. Effectively, after the violation alarm, emitted by the United States Environmental Protection Agency – EPA -, Volkswagen admitted to using a software that enables the vehicle to recognize that is submitted to a test and also, it enables so to modify during the test the NOx emissions.  But, the recognition of test environment is sufficient in itself to indicate the defeat device presence?

Following the declarations of Volkswagen, the focus was the control strategies of emissions used by manufacturers, since it should be laid down if these strategies can be an illicit use of defeat device or if these strategies may represent an illicit application of derogations provided for in the Regulation.

The system of checks to be carried out by Member States underwent a transformation in 2015. Before 2015 no Member States applied specific methods of ascertainment of possible used defeat device. Differently, after 2015 some Member States began to use several means of proof and to this day, however, there is no conformity and comparability of all the methods used by the Member States to evaluate the compliance with the EU rules in the field of defeat device. In accordance with the findings of the above-mentioned parliamentary inquiry, the authorities and technical services expect interpretative guidance of Commission, particularly about the limits of the derogations use provided for in European legislation.

The goal is, therefore, a common interpretation of Regulation of 2007. As the Director of International Council of Clean Transportation – ICCT – staff Peter Mock emphasizes in a report, published on ICCT website on April 2016, peculiar and singular in the Dieselgate affair has been the German experience.
The Minister for Transport, Alexander Dobrindt, sharing the cars test results, announced that, starting April 2016, car companies should have declared the eventual installation of a defeat device with a detailed illustration of the mode of operation, but also the clarification of the reason of defeat devices utilisation. The test results showed indeed that 22 of 53 cars tested had produced a high level of NOx emissions without an acceptable explanation by the Member States.

Similar exhortation lacked from the others Member States waiting for the Commission’s opinion.



Since diesel engines gained popularity several companies began to develop different technologies to reduce emissions car. That sounds like something revolutionary: you can still have your diesel car, but a less polluting car; the perfect solution for all our troubles. Unfortunately, it is not that easy; new technologies come with a high cost. Some of these technologies were known before Dieselgate “as long as emissions were only measured in the lab there was not a big incentive for car manufacturers to check that car emissions were also controlled outside the lab“, explained to us Cècile Favre, EU Technical Affairs Manager at the Association for Emissions Control by Catalyst – AECC -. Car manufacturers weren’t interested in using them or they were using them but not to their full potential, for example switching them off outside the laboratory test with the defeat device.

The most surprising thing is that the reason why the technologies haven’t been used and installed on vehicles is not really connected to their cost for car manufacturers. It’s not so much about the cost of production, the cost to put them in a car, but rather about the cost of sale, about the cost of maintenance during the lifetime of the vehicle. “It’s the burden on the customer” said Cècile Favre when she spoke to us about the new technologies that her association is in charge of developing.

Considering that the most dangerous emissions for diesel engines are PM, particular matter and NOx, nitrogen oxides, we are going to take into account the technologies developed to cope with these emissions. As Cècile Favre told us, for PM you have the particulate filters which keep the particles inside. When the gas comes in, the particles remain stuck into the filter and from time to time you have to burn the particles in the filter. So there is some engine management to do that and then you start again to accumulate particles. These have been mandatory for Euro 5 vehicles  since 2009. For NOx there are the after treatment systems for diesel engines that have started to be introduced with the Euro-6 . “After treatment” means everything which is on the exhaust line: you have the engine and everything after the engine is the after treatment and for NOx we refer to either the Nox absorber or the Selective Catalytic Reduction for NOx or even a combination of the two. The SCR systems use ammonia injected into the exhaust, possibly using a reagent such us urea solution. So you need to inject urea for the system to become operational, but the more urea you inject, the faster the urea tank will deplete. For the NOx absorbers you need to use a bit of fuel. In both cases there is a direct impact on the customer who has to use more money and that can explain why if you are not obliged to use these technologies, you won’t.

“A direct money aspect is much more effective than the environmental one. Environment or low emissions are not a selling argument for customers, I’m afraid” says Cècile Favre adding that in order to improve the use of the technologies the legislation should be developed properly to force the proper control of emissions or to give manufacturers and customers some incentives to buy a low emissions car. For example a city could decide that only car with emissions below 1.5 are allowed to drive into the city center. That can become a selling argument, because the customer has an incentive to buy a cleaner vehicle.



Industries say that they need time to gradually adapt new technologies to market and customers’ needs. So the high conformity factor is justified.

Lots of experts don’t agree with this perspective. The scientist Peter Mock – ICCT – respond that the transitional periods claimed by the car manufacturers are questionable:”The conformity factor doesn’t make much sense because if you look at the vehicles that are coming into the market now they are better about emissions. They have a conformity factor which is below 1. Technically it is still possible.

What we get from these words is that it is not a question of time, because the technologies are already available. Car manufacturers just have to use them and in order to do that, of course, they need to spend money. Instead, they insist on keeping an high level of conformity factor in the Regulation. “That’s politics. So that even those car manufacturers which are not as advanced, they can comply with that in the future“, said in response Peter Mock.

So we would be thinking by now that car industries are just making up some excuses. Is it more shocking for them to spend a bit of money on using the technologies that are already available or to see the death statistics rising year after year?



We interviewed the Fiat Group engineer Giovanni Cipolla about the future scenario and alternatively powered vehicles.  He described four different alternatively powered vehicles: electric cars, hybrid cars, fuel cell and automatic cars.

He believes that in the next ten or twenty years there won’t be any internal combustion engines but electric ones. Electric motor still existed back in the past and they have been successful for a while thank to the lack of combustion. However the problem was the lead battery that was very heavy and still today it doesn’t have enough self-sufficiency by road. In his opinion, the best idea would be to have an electric vehicle for a short distance and a traditional car for long journeys, In this scenario, the user won’t travel in his own car but he will use a car sharing system. So car manufacturers instead of producing cars for users will produce vehicles for hire companies. The keystone of this development is the change of attitude.

Today electric cars are already on the road, but one of the main problem concerns the small number of charging infrastructures because you need a lot of them in order to allow users to move easily. Moreover, there isn’t a huge network of stations that are fast in charging cars batteries when they run out.

Changes need time. Considering the above troubles about electric cars, a transition facility is represented by hybrid cars. They are made up of both gasoline and electric engines which are connected in the car. So you can the advantages of an electric engine that doesn’t pollute and of a gasoline engine that can work for long distance when the battery run out, but also it is able to be a power supply for the battery“.

What about fuel cell? Fuel cell is a system based on the combustion of oxygen with hydrogen that reacting together generated H2O and so energy. This process is not polluting, but it is very expensive, so nowadays it is used for spaceship and military industry.

The innovation that needs more time to develop is the automatic car. This is not science fiction, but technology which has amazing advantages because it will change the image of the city: less traffic, less pollution, less stress to look for a parking, but more security, more space for pedestrians and cleaner air. Changes come with brave choices. In order to speed up the development of alternatively powered vehicles, it is necessary choices from the top-brass involving more public incentives and funding for car manufacturers to change their production.

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