The diesel dilemma

(As of 2018)

as Rudolf Diesel (1858-1913) submitted his fundamental patent on February 22nd, 1893, his goal was an internal combustion engine with optimal efficiency that should come as close as possible to the theoretical ideal (the Carnot process).
The first prototype ran at Maschinenfabrik Augsburg (later MAN) in 1893, and after many improvements, the first practical model came in 1897.
Now the diesel engine began its journey into the world.

After numerous further developments, it now dominates the drive of aggregates, construction machinery, trucks, mobile cranes, armored vehicles, ships, tractors, vans, and a large number of passenger cars are equipped with diesel engines that consume significantly less fuel than gasoline engines of the same power. Not to forget the diesel locomotives that run in many countries around the world.

The diesel engine is perhaps the last, very great German engineering achievement to conquer the world!

But recently the diesel engine has fallen into disrepute and some eco-fundamentalists would like to ban this globally successful drive altogether.

What happened?
The catchphrase of "global warming" is heard in all media, and the majority of politicians want to implement drastic measures in Europe to limit this drastic climate change.

The combustion of fossil fuels (coal, oil, natural gas) is considered to be the most important cause of climate change and has increased steadily since the beginning of the industrial revolution 250 years ago. This produces large quantities of Carbon dioxide (CO2), which as a "greenhouse gas" is considered to be the main cause of man-made global warming.

This concept is not without controversy. But I won't go into that further, because in our “post-factual” age it is less the facts that are decisive than the opinion - guided by the mass media.
And this majority opinion is clear: The burning of coal, natural gas and oil must stop!

Pressured to take action, legislators opted for half-hearted solutions, first for road transport.
One did not dare to directly reduce the consumption per car through legal regulations. That would have been too deep an encroachment on buying behavior and customer wishes. So it was decided to limit the “fleet consumption”, i.e. the average fuel consumption of all models manufactured by a manufacturer. The fact that standardized measuring methods were necessary for this, which - like all regulations - are flexible, should not concern us further here.

Limit values for the fleet consumption:
From 2015: 130 g CO2 per km,
For petrol corresponds to 5.49 L / 100 km. With diesel 4.9 L / 100 km.
From 2019: 95 g CO2 per km,
For petrol corresponds to 4 L / 100 km. For diesel 3.58 L / 100 km.
From 2030: 59 g COper km,[1]
Corresponds to 2.5 L / 100 km for petrol. With diesel 2.2 L / 100 km.
The regulation, which will apply from 2030, can only be met if a substantial part of the fleet consists of zero emission vehicles.

The required fleet consumption put German manufacturers in particular under pressure. They sell a particularly large number of “premium vehicles” and SUVs that are large, well equipped and correspondingly heavy and cannot drive as economically as a small car.

What to do? One way out was with highly developed diesel engines, which save up to 30% fuel compared to comparable gasoline engines and are even more pleasant to drive on top of that.

Unfortunately, there are other regulations that cause problems: namely limit values for fine dust, carbon monoxide, soot, nitrogen oxide, etc., which have also been continuously tightened since 1992.
In 2006, for example, the limit value for Nitrogen oxides (NOx) in the EU for passenger cars (Euro 5 emissions standard) at 160 mg per kilometer, in the USA at 30 mg per kilometer; a value that caused technical problems.
Establishing such limit values is difficult. There are no clear scientific criteria, so limit values are negotiated and finally legally stipulated.

In order to meet the legal requirements, the exhaust gas from both petrol and diesel engines must be treated. This requires a small "chemical factory" that catalytically converts the gaseous pollutants into more harmless substances and - at least in the case of diesel - a fine dust filter for the soot particles.
Here the diesel engine is at a disadvantage compared to the gasoline engine.
As a compression-ignition engine, the diesel works with higher combustion chamber temperatures than a gasoline engine; the main reason for the better efficiency, but also for a higher proportion of nitrogen oxides and other pollutants in the exhaust gas. The direct fuel injection into the cylinder makes the mixture more difficult and creates more fine dust or soot. The diesel engine, for example, requires more complex exhaust gas purification, which takes up space and costs money. There are currently two options for neutralizing nitrogen oxides:
1. An absorber catalyst is used.
2. A urea solution called "AdBlue" is injected into the exhaust gas. AdBlue decomposes to ammonia at a sufficient temperature (170 degrees C), which reduces the nitrogen oxides to nitrogen and water. This requires a tank for AdBlue, injection, lines, sensors, electronics, etc.
These two options can be combined.

The situation is exacerbated by environmental protection. So z. For example, nitrogen oxides do not exceed the limit of 40 micrograms (1 µg = 1 / 1,000,000 g = 1 millionth of a g) per cubic meter of air even on busy roads. In the workplace, the limit is 950 micrograms, more than twenty times that. The 40 µg are not scientifically well secured, but rather an ideological value of the WHO that the EU has adopted. In the USA 103 micrograms apply, even in California, which is particularly strict in terms of environmental issues, 57 micrograms.

Hardly any thought was given to other oil consumers. "According to the Naturschutzbund Deutschland, the 15 largest container ships emit as many pollutants as 750 million cars each year." (Photo no.33 from August 18, 2017). There are 45 million cars in Germany and 900 million worldwide (Internet).

According to, around 750 gigatons of carbon dioxide escape from natural sources into the atmosphere. 33 gigatons are released annually by human hands, i.e. only around 4.4% of the total emissions. It remains to be seen in this calculation how much carbon dioxide is bound again through the assimilation of plants and in the seas, and how strong the decline in assimilation is through cutting down the forests, sealing the soil, etc.

It is better not to mention that a cattle produces more carbon dioxide than an average car that drives 15,000 km per year. In addition, a cattle produces 72 kg of methane per year, which is at least 20 times more effective as a greenhouse gas than carbon dioxide.
However, as herbivores, cattle are integrated into the natural cycle and cannot release fossil carbon that has been removed from the natural cycle for thousands of years.

Since nuclear power plants have to be switched off as too dangerous, only "eco-energy" remains: sun, wind, hydropower, renewable raw materials, biogas, geothermal energy, tides, etc.
The electric motor with accumulator is currently being propagated for cars. Alternatives such as fuel cells, biogas etc. are hardly taken seriously in Germany.

The car as an air polluter
The car with its excessive energy consumption soon became the focus of interest. The eco-activists demanded more economical cars, but consumers were buying ever larger and therefore heavier models that use too much fuel and blow out too many pollutants, especially nitrogen oxides.

“If you light a few candles in your living room, the EU limit of 40 micrograms will soon be exceeded. And if you let several flames burn at the same time on your gas stove, you will also quickly be well above the limit value of 950 micrograms for the workplace.
It is not even certain that the diesel engine is primarily or even solely responsible for the nitrogen oxide. In Oldenburg, the road around a measuring station was closed due to a marathon. Nevertheless, there were increased nitric oxide values. "        (Focus-online, January 29, 19, 19:30).

In order to comply with the limit value of 40 micrograms per cubic meter of air, diesel vehicles are threatened with driving bans in many German cities, which are enforced by court rulings. The location of the measuring stations (distance from the road, altitude, etc.) also plays a role here. Here, most EU countries - where the same regulations apply - are more generous than the fussy Germans.

Due to the strict enforcement of the regulations in Germany, the usability of several million diesel cars is restricted; these lose value and billions of dollars in losses are incurred that gullible diesel drivers have to bear.

Was it cheated?
At first glance, the situation seems clear: legal regulations must be complied with.
But the practice is - as always - more complicated.
AdBlue is not a dangerous liquid, but it is a bit corrosive and should not be splashed on the silk dress. In contrast to the truck, whose drivers are professionals, people didn't want to refill AdBlue when they refuel, but only during the inspections. To do this, the AdBlue tank would have to hold approx. 30 liters, about a third of the volume of the fuel tank. Such a large tank would have made the trunk smaller and left too little space for the installation of an expensive stereo system (which the automobile manufacturer makes a lot of money on), for bulky luggage such as golf clubs, etc.

So there was probably an agreement between various manufacturers to limit the AdBlue tank to approx. 7 liters. The rest of the work had to be done by the computer control with the following (and possibly other) tricks:
1. The control recognizes whether the car is running on the test bench and then switches to a special program for complete exhaust gas cleaning, which is only partially effective in normal operation. This is a violation of regulations and you have to be accused of fraud.
2. In normal operation, as much AdBlue as possible must be saved, e. B. through large "thermal windows".
Since AdBlue only decomposes at around 170 degrees C, it makes no sense to inject it into the exhaust at lower temperatures. The injection is then switched off and, on short journeys and very low outside temperatures, the exhaust gas cleaning by AdBlue is largely eliminated. The thermal window can be stretched, with the argument of protecting the engine.
3. Further manipulations are possible and in some cases have already been implemented: Switching off the AdBlue injection at high speeds, strong acceleration or from a certain height above sea level. (Der Spiegel, No. 39/2017 p. 69).

Depending on the operating mode, the required exhaust gas cleaning only works for a fraction of the operating hours; far more nitrogen oxide is blown into the environment than permitted by law.

The consequences of the violations of the law were fines billions and billions in damages for vehicle owners in the USA, as well as legal proceedings against senior managers in the USA and Germany. Diesel drivers also claim damages in Germany.

How did this fraud come about?
Apparently the decision-makers of several automobile factories refused to admit that a scientifically poorly founded limit value for nitrogen oxides could be enforced with all severity by the authorities. So these car bosses have embarked on a risky game that, on sober observation, could not go well.

How could one hope that measurements would be taken exclusively on the test bench and that nobody would notice if a special test bench program met all legal requirements, but this program was completely or partially switched off during normal operation?

Or you can find all possible reasons (temperature, speed, acceleration, etc.) to let the exhaust gas cleaning fail in a large part of the operating states.

And should nobody notice these illegal manipulations?
Experience has shown that one always has to expect that swindles will be exposed sooner or later.
In this case, there are enough universities and other research institutes that can carry out exhaust gas measurements; on the test bench and on the street. Last but not least, there is also the competition, which may have an interest in uncovering a competitor's manipulations.

Personally, as the former head of development in a tire factory with product responsibility for an overly critical safety component (pneumatic tires), it is completely incomprehensible that responsible designers from respected large corporations could get involved in such a risky game. But I probably come from a different generation of engineers for whom “Made in Germany” was a top priority, and deliberate fraud by German engineers seemed unthinkable.

Or is the diesel scam just an expression of the moral decline of our society, as can also be seen in computer fraud, criminal clans, financial manipulation, squatting, parallel societies, lawless areas, etc.?

Final grade:
[1] This value has recently been tightened to 47.5 g CO2/km. The aim is to virtually abolish combustion engines for cars.

Addendum 2019:
The classification of the electric car as "emission-free" (zero emission) is simply nonsense. It can only be emission-free if all steps, from production onwards, are powered by green electricity. If you take into account the production of the battery and the current energy mix in electricity generation, the CO2-According to a study by the Info-Institut, the carbon footprint of an electric car is even worse than that of a diesel:

Addendum 2023:
How the emissions fraud was uncovered (as expected) and who is responsible for this criminal manipulation is described in a detailed, three-part series "The Winterkorn File" in "The Pioneer Briefing" on December 27, 28 and 29, 2023.
When the fraud was discovered, VW behaved as clumsily as possible towards the US authorities and made things even worse.