by Tom Gresham

The diesel fuel market has faced an array of challenges in recent years. Regulatory and marketplace pressures to reduce emissions and increase fuel efficiency have required an emphasis on investing in innovation and showing clearcut results. Meanwhile, electric and hydrogen fuel cell trucks are attracting attention as potential long-term players in the commercial truck field.

Still, advocates say the diesel market remains as strong and steadfast as ever, and its demonstrated capacity to adapt and evolve with changing times suggests diesel’s long-term prospects are promising.

“During the pandemic, we saw supply chains substantially disrupted through unpredictable demand,” said Len Copeland, product marketing manager, Detroit, Daimler Trucks North America. “The recovery and adjustments from this has created the current freight market where demand for commercial trucks has rarely been higher. Although (environmental, social and governance) pressures, regulatory actions and other forces are driving a high level of interest for alternative propulsion technologies, diesel remains king, and they have never been more efficient, reliable or cost-effective.”

David Hughes, senior vice president of sales for Pilot Flying J, agreed, saying the current state of the diesel market is “very healthy.” In fact, three out of four trucks on the road are diesel-powered and 97 percent of large, over-the-road Class 8 trucks are diesel, according to the Diesel Technology Forum, a nonprofit association that represents companies operating in diesel engines, equipment and fuels.


Diesel has advantages of power density, durability and reliability that will continue to make it a popular choice for commercial trucks for decades, especially for long distances and heavy loads, said Allen Schaeffer, executive director of the Diesel Technology Forum.

Copeland said diesel holds a prominent place as “the established power source” for commercial trucks because of several advantages that figure to remain in the coming years.

“Key among these being physics, chemistry and a mature infrastructure,” Copeland said. “Diesel is easily transportable with existing infrastructure and does not require significant storage considerations such as pressures and temperatures. Diesel is also extremely energy dense, lending itself to the high torque requirements of Class 8 trucking. It also has a 125-year ‘first to market’ advantage.”

Hughes sees diesel as operating in a position of strength in the current marketplace, which does not yet offer a formidable alternative.

“The biggest advantage of diesel right now is that it’s a reliable and efficient technology being used across major (original equipment manufacturers),” Hughes said. “Currently, the country doesn’t have the infrastructure needed to support electric or hydrogen fuel cell trucks, so they are not a viable option for most long-haul uses.”

Key to the positive signs of the diesel market’s future is how resilient and adaptable it has been during its history and how its inherent advantages figure to remain consistent going forward, advocates said. Copeland noted that “diesel combustion engines have been around for 125-plus years with continuous evolution.

“The biggest trends currently are the same as they have been for a long time – fuel efficiency, reliability and emission reductions.”

Copeland said the recent past shows an example of diesel encountering an array of challenges and continuing to survive and thrive.

“Some industry experts refer to the 2000s as the ‘lost decade,’ where regulations forced technology too quickly and resulted in diminished fuel economy and reliability of diesel with significantly higher upfront cost,” Copeland said. “It wasn’t until 2010 that the emission technology and the cost paid for it resulted in a net fuel economy payback and improvement in reliability. Diesel engines today are as stable as they were pre-2000 in terms of reliability, only they are highly efficient and have a minuscule amount of (nitrogen oxides) and (particulate matter).”


Hughes believes a crucial development for the health of the diesel market has been its evolution with new trends and the “remarkable” job the industry has done adopting clean diesel technology.

“More than 50 percent of the largest trucks on the road (Class 7 and 8) are operating with the newest generation diesel technology that is delivering significant fuel savings and environmental benefits,” Hughes said. “Pilot Flying J is committed to providing our customers with high quality fuels and is one of the largest sellers of renewable diesel and bio-diesel in the United States. We have seen and continue to see an increase in bio-diesel and renewable diesel availability across the United States.”

The Diesel Technology Forum highlights the dramatic improvements in diesel-related emissions that have accompanied adoption of the new technology. According to the forum, emissions from heavy-duty diesel trucks, buses and other vehicles have been reduced by 95 percent for nitrogen oxides and 90 percent for particulate emissions in the past 20 years. It would take 60 new trucks to generate the same emissions as a single truck manufactured in 1988, according to the organization.

New advanced technology diesel commercial trucks in the U.S. now represent 49 percent of all diesel commercial vehicles on the road, according to the Diesel Technology Forum. The more energy-efficient trucks have lower emissions and continue to grow in popularity. The forum claims there have been more than 230 million fewer tons of emissions due to diesel trucks since progressively cleaner diesel trucks were introduced in 2007 and 2011. That represents emissions and fuel savings equivalent to converting 43 million cars to all-electric, Schaeffer said.

“Results from the newest technology diesel vehicles are growing in the form of cleaner air and fewer greenhouse gasses in communities all around the country,” Schaeffer said.

Copeland said upcoming emission regulations updates likely will prompt major changes in diesel offerings, and those such as Daimler who provide diesel technology will need to continue to evolve and strengthen their products to meet regulatory requirements and to serve customers.

“The use of biobased diesel fuels – that includes biodiesel and renewable diesel fuel – can greatly reduce greenhouse gas emissions today, as is proven in California where biodiesel and renewable diesel fuel used in diesel vehicles reduced more than three times the greenhouse gas emissions, as did electric vehicles,” Schaeffer said.


Looking ahead, Hughes believes diesel fuel will remain a mainstay in the commercial market, continuing to serve as the dominant preferred fuel in the next two decades.

“According to IHS Markit, 80 percent of commercial trucks will be powered by diesel by 2040,” Hughes said. “We expect that EV adoption will be slower for commercial trucks than passenger vehicles.”

Meanwhile, diesel technology appears poised to continue to improve and become more efficient.

“The technology for heavy-duty diesel engines has certainly not reached its peak,” Steve Whelan, global development and application center leader at engineering consultancy Horiba Mira, told Automotive World in 2021. “There are well-known technologies that can be deployed to improve both regulated emissions and efficiency.”

Truck and engine manufacturers and stakeholders are among those involved with the U.S. Environmental Protection Agency’s Cleaner Trucks Initiative that will update emissions standards for heavy-duty trucks, according to the Diesel Technology Forum. The first rules, to be finalized this year, will apply to heavy-duty vehicles starting in model year 2027. The EPA last revised nitrogen oxides standards for on-highway heavy-duty trucks and engines in 2001.

“While the promise of zero-emission commercial vehicles is growing, it may be many years, if not a decade or more, before these solutions enter the fleet in significant numbers,” Schaeffer said. “In the meantime, continued progress on improving air quality and lowering greenhouse gas emissions is essential and… is being delivered primarily by investments in the new generation diesels.”



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