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Should we still be buying the new (latest generation) diesel cars?
The Dieselgate scandal in 2015 totally compromised the image of the diesel engine, discrediting the technology: accused of being more polluting in terms of nitrogen oxide (NOx) than the current standards, it was condemned by Governments and therefore car drivers, who are consequently buying fewer and fewer of them in favour of petrol cars.
But the fact remains that around 2/3 of private vehicles with Luxembourg plates are still running on diesel.
This means that many motorists have no idea which option to go for, delaying their decision to buy or even putting it off altogether. But what is the real story?
The ACL has the information you need:
A European study shows that the new diesels emit far less nitrogen dioxide than the previous generation.
According to a study published by the European Automobile Manufacturers (EAMA), the new diesel engines meeting the current Euro 6d-Temp standard are much less polluting than the old Euro 5 (2009-2014) versions, even in real traffic conditions. This is mainly due to tougher certification tests.
The new WLTP test cycle (which manufacturers have been using for certification since 2018 and which comes into force in Luxembourg on March 1 for calculating car tax) is actually designed to give results closer to reality than the old NEDC cycle that it replaces, and all the more so because it also includes road tests in real conditions known as conditions RDE (Real Driving Emissions). As part of the study, 270 Euro 6 diesel vehicles were road-tested by drivers from the authorities from the particular countries and not by the manufacturers according to the EAMA. Our colleagues at the ADAC, an automobile club and leading authority in Germany, confirms the data.
Engines meeting the emission standards
Data collected shows that all of the vehicles tested have lower nitrogen dioxide (NOx) emissions than the current RDE test threshold, urban cycle included.
Automobile manufacturers have put major investment into developing technology for processing exhaust gases for a rapid delivery of such a massive reduction in NOx emissions, also addressing other pollutants such as soot particles*. With such conclusive results and lower CO2 emissions than petrol engines, modern diesel cars supported by fleet renewal policies combined with alternative engine options will continue to play an important part in reducing CO2 emissions in line with air quality objectives.
The diesel engine is still the best solution for long distances.
With lower fuel consumption (and therefore lower CO2 emissions), diesel vehicles often go a long way between refuelling stops, which is an undeniable advantage for long-distance driving, and are more economical than petrol.
For the same power output, a diesel engine consumes an average of 25 to 35% less fuel than a petrol engine. This can be explained by various factors, including the laws of thermodynamics and the fact that a litre of diesel contains about 10% more energy than a litre of petrol. This means that, even if both engines had the same levels of efficiency, a diesel engine would go further between refuelling stops.
Finally, if you are looking for a new vehicle and travel long distances (>25,000 km/year), the diesel engine’s greater energy concentration and energy efficiency make it the best current choice, also meeting the pollution standards in force.
*Soot particle pollution
Diesel engines are known to emit soot particles (the puff of black smoke that comes out of the exhaust pipe). This problem was solved with the introduction of the particulate filter, which has been compulsory in Europe since 2011, and the introduction of the Euro 5 standard. And it’s been a long time since we saw any of these puffs of smoke coming out of exhaust pipes! But you might have read in the January 2020 papers that a European study tested two modern diesel vehicles (Euro 6d-Temp) that emitted up to 1,000 times more particles than the standard allows. Luckily, this is inaccurate information, as, although correct, this measure only represented a tiny proportion of the test during which the particulate filter is regenerated (cleaned). In actual fact, particulate emission values were met throughout the test as a whole. We can only conclude that this statement regarding diesel engines was touted by people either with little expertise in the matter or who were simply ill-intentioned.