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Are we seeing the demise of the passenger car diesel engine? You would think that with all the recent negative publicity surrounding the oil burner, that no one in their right minds would consider a diesel engine for personal use.

But that really isn’t the case. First of all, most prime movers around the world are powered by diesel. Whether that engine sits in the bowels of a ship, is used to haul 100 railroad wagons or just to transport forty tons of produce to your neighbourhood supermarket, diesel will continue to be the primary choice for these duties. The secret is of course that the engine works at much higher thermal efficiencies than a regular petrol engine. Over the years, passenger car manufacturers have refined and honed the diesel engine, moving away from the distinct agrarian clatter of the self-igniting powerplant to a unit that generally is cleaner than a petrol engine on many fronts.

Diesel engines tend to operate under much higher pressures – compression ratios are twice that in petrol engines and diesel is injected under very high pressure. The basic construct of a diesel engine is much more robust and the mechanism is so reliable that maintenance is at a minimum. There are very good chances that a modern diesel engine will never need to opened out during the life of the car. These are all characteristics that seem, in my opinion, to push for an environmentally friendly tag.

The gravest problem that diesel has faced recently is the association with cheating. Volkswagen did no one any favours by gaming their engines for tests and the result has been an association of the fuel with a dirty act. To be fair, the brand would have suffered more if they had actually cheated on fuel efficiency numbers instead of pollution figures.

Thankfully the punitive penalties of the US market have not followed the brand to the home market. Germany’s transport ministry has decided to let the industry self-police themselves to an extent, with the costs going towards software relflash of Euro 5 and 6 cars being borne by the auto makers. In addition, manufacturers will incentivise drivers of older cars to move to new cleaner offerings (usually electric, hybrid or CNG, which we consider is an overkill) with thousands of Euros of price rebates. The condition is that these older cars need to get scrapped.

Of course, most green advocates see this as a means of side-stepping the core issue of an unclean powerplant. Many countries seem to be falling out of love with the highly efficient oil burner. India’s National Green Tribunal has placed a ban on the use of diesel passenger cars that are more than 10 years and this is seen as one of the reasons behind the reduction in the weightage of diesel cars to the whole from 47% in 2012-13 to 27% last year. Other factors that have also helped this trend is higher taxation and the inherent higher manufacturing cost of the car.

All of this is rather rhetorical for the buyer in the GCC area. Pollution standards aren’t really cutting edge anyway, but the draw of the diesel does not exist in a market where the fuel is typically priced higher than petrol. And then there is the pattern of driving that differentiates drivers of the two fuels, with diesel offering so much more torque and lower revs. Not quite the building blocks of the putative race car driver we have on the roads.

To top that, Mazda has also just announced a new generation of petrol engine that will do away with spark ignition, in essence taking away diesel’s one major difference. But does that mean that diesel is running into a dead end?

The car companies are reasonably confident that they have the technology to see the fuel well into the future. Ad Blue is only one of the available paths – where a compound of urea is used to scrub the NOx emissions to the level that they are no longer an issue. That, higher operation pressures, lower sulphur and better engine management are all solutions. But the technology is being peddled by companies that are also pushing electric and hybrid engine tech. They are protecting todays investment, but also are ready to take tomorrow’s money. Perhaps we really need government’s to declare their all-electric cut off dates (India at 2030, Europe at 2040 and so on) to really quantify the value of diesel in the powertrain.

This opinion piece first appeared here.

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