Diesel Vehicles Guide

Diesel vehicles have played a significant role in the automotive landscape, offering efficiency and power that made them popular choices for a variety of applications. However, their journey has been marked by both acclaim and controversy. In this article, we will delve into the history, technology, advantages, controversies, and the future prospects of diesel vehicles.

The Early Days of Diesel

The diesel engine, invented by Rudolf Diesel in the late 19th century, was initially designed to run on vegetable oil. Diesel envisioned an engine that could provide a more efficient alternative to the gasoline engines of the time. Diesel engines operate on a principle of compression ignition, where air is compressed to a high temperature, and fuel is injected, igniting spontaneously.

Advantages of Diesel Technology

• Fuel Efficiency: Diesel engines are known for their superior fuel efficiency compared to gasoline engines. This efficiency is due to the higher energy content of diesel fuel and the higher compression ratios in diesel engines.

• Torque and Towing Capacity: Diesel engines are renowned for their high torque output, making them ideal for heavy-duty applications such as trucks and towing. The robust low-end torque of diesel engines allows for better pulling power and acceleration.

• Longevity: Diesel engines are often associated with longevity and durability. Their robust construction and lower RPM operation contribute to a longer lifespan, making them suitable for commercial and industrial use.

• Better Fuel Economy: Diesel engines generally offer better miles per gallon (MPG) compared to gasoline engines. This can result in lower fuel costs over the long term, especially for vehicles with high mileage.

Controversies Surrounding Diesel Vehicles

• Emissions and Air Quality: Diesel engines have been at the center of environmental controversies due to the emission of pollutants, particularly nitrogen oxides (NOx) and particulate matter. The combustion process in diesel engines produces higher levels of these pollutants compared to gasoline engines.

• Volkswagen Emissions Scandal: In 2015, Volkswagen (VW) became embroiled in a major scandal when it was revealed that the company had installed software in certain diesel vehicles to manipulate emissions tests. This scandal not only damaged the reputation of diesel vehicles but also led to increased scrutiny of diesel emissions worldwide.

• Regulatory Changes: Stringent emission standards in various countries have led to the implementation of strict regulations for diesel vehicles. This has prompted automakers to invest in cleaner diesel technologies or shift their focus to alternative powertrains.

The Transition to Clean Diesel

In response to environmental concerns and regulatory pressures, the automotive industry has been working on developing cleaner diesel technologies. Key advancements include:

• Selective Catalytic Reduction (SCR): SCR technology involves injecting a urea-based solution into the exhaust stream to convert NOx emissions into nitrogen and water. Many modern diesel vehicles use SCR systems to meet stringent emission standards.

• Diesel Particulate Filters (DPF): DPFs trap and remove particulate matter from the exhaust gases of diesel engines. These filters have become a standard feature in many diesel vehicles, helping reduce particulate emissions.

• Common Rail Fuel Injection: Common rail systems enhance fuel atomization and combustion efficiency, leading to cleaner and more fuel-efficient diesel engines.

• Euro 6 Standards: European emission standards, known as Euro 6, set stringent limits on pollutant emissions. Vehicles meeting these standards employ advanced emission control technologies to reduce NOx and particulate emissions.

More about Selective Catalytic Reduction (SCR)

Used correctly, SCR is reported to help reduce the level of Nitrogen Oxide (NOx) emissions by up to 90% and could potentially reduce the amount of fuel used by between 3% and 5%. Vehicles with SCR are fitted with an additional tank, specifically designed to store a liquid-reductant agent known as AdBlue®, which you can buy from selected vehicle dealers and fuel stations.

Your vehicle manual will tell you which warning lights and sounds indicate that it is time to refill the tank and how to go about it. It is important to pay swift attention to these warning signs, as ignoring them could see your vehicle go into “limp home” mode (run on reduced power) or it may simply not re-start once the ignition has been switched off. Just like fuel, the cost of refilling the tank with AdBlue® is the responsibility of the individual vehicle driver or their employer. However, where the service schedule states that the fluid should be changed (rather than topped up), and you have a maintenance contract as part of your agreement, the cost will be covered.

More about Diesel Particulate Filter (DPF)

Almost all diesel vehicles are now fitted with a DPF designed to catch soot in the exhaust and prevent it from entering the environment. To keep everything running smoothly, the filter needs to be regularly emptied using a process known as regeneration. This is when the soot is burnt off at a high temperature, leaving just a small residue of ash. It’s a process that takes place automatically when driving at motorway speeds because the exhaust reaches a high enough temperature for the regeneration process to occur.

On the other hand, if a vehicle is mainly driven for shorter distances, at slower speeds, the cleaning process will not take place frequently enough to keep the filter clean. In these circumstances, most vehicles will initiate a forced regeneration by boosting the exhaust temperature to a point where regeneration will occur.

However, this can mean that you need to keep driving for 10 minutes or so at speeds greater than 40mph until the process is complete and the warning light clears. If the warning light is ignored, soot levels will continue to rise, and the vehicle may enter a ‘restricted performance mode’ to limit any further damage. At this point, the vehicle will need professional attention to clean or even replace the DPF. This can easily cost upwards of £1,000 and is not covered by either your warranty or any maintenance agreement you may have with us.

To protect your DPF and keep it running smoothly, it is important to follow the guidance found in your vehicle handbook and, if any warning lights come on, take the recommended action immediately.

The Future of Diesel Vehicles

• Hybrid and Electric Technologies: Many automakers are investing in hybrid and electric technologies to complement or replace traditional diesel powertrains. Hybrid diesel-electric and plug-in hybrid diesel vehicles aim to provide cleaner options while retaining the benefits of diesel efficiency.

• Advanced Combustion Technologies: Ongoing research and development focus on improving internal combustion engine efficiency and reducing emissions. Advanced combustion technologies, such as homogeneous charge compression ignition (HCCI), aim to achieve cleaner and more fuel-efficient diesel engines.

• Alternative Fuels: Exploration of alternative fuels, such as synthetic fuels and biofuels, offers the potential to reduce the environmental impact of diesel vehicles. These fuels can be derived from renewable sources, mitigating the carbon footprint of diesel engines.

In Summary

Diesel vehicles have undergone a remarkable journey, from their inception as efficient engines to facing environmental controversies and regulatory challenges. The automotive industry's response to these challenges has led to the development of cleaner diesel technologies and a shift toward alternative powertrains. While the future of diesel vehicles may see a decline in traditional diesel-only models, advancements in hybridization, electrification, and cleaner combustion technologies signal a continued role for diesel in the evolving automotive landscape. The journey of diesel vehicles reflects the industry's commitment to balancing efficiency with environmental responsibility in the pursuit of sustainable transportation.

This article was written and published by Christopher Lowe.