What Does The Future Of Heavy-Duty Diesel Trucks Look Like?

• October 19, 2023
• Story By
  Mike McGlothlin

You’ve read all the headlines. Battery electric vehicles (BEVs) have arrived. Diesel is dead…. Not so fast. Per every meaningful metric that takes the automotive industry’s future into account, it’s clear that diesel propulsion will be with us for at least another 10 years, if not another quarter century. This is especially true in the heavy-duty pickup truck segment, where dragging a 20,000-pound trailer through the mountains is often the order of the day. Here, electric has a lot more to prove than it does in the commuter car sector. But exactly why will diesel continue to dominate this particular niche within the automotive landscape?

To understand how diesel will survive the BEV takeover, we’ll start at the beginning and work our way forward. From an emissions standpoint, the diesel internal combustion engine (ICE) has cleaned up its act tremendously. And as more stringent NOx standards loom, they will become even cleaner in the years ahead—all while turning out gargantuan torque numbers. In the next five to seven years, expect Ford’s Power Stroke, Ram's Cummins and perhaps even GM’s Duramax to make 1,300 to 1,400 lb-ft right off the showroom floor. Below, we’ll explain how and why we expect The Big Three to get there.

How It Started

Because the design of every ICE is emissions-driven, it’s important to start there. When diesel debuted in the ¾-ton and larger pickup truck segment via GM’s 130 hp, 240 lb-ft of torque 6.2L V8 in 1982, there were no nitrogen oxide (NOx) or particulate matter (PM) regulations to speak of. As a result, that engine—along with the 170 hp, 310 lb-ft International Harvester 6.9L V8 that Ford introduced in 1983—could easily be classified as “dirty.” By 1985, the first NOx standard of 10.7 g/bhp-hr was implemented and a 0.60 g/bhp-hr PM regulation became law in 1988—right when the revolutionary, turbocharged and direct injection, 400 lb-ft 5.9L Cummins inline-six arrived in Dodge trucks.

How It’s Going

It can’t be understated that, as NOx and PM emissions standards became more and more stringent, not only did The Big Three meet the tighter emissions standards, but they also managed to continue to build more powerful engines. Case in point, Ford’s F-250 and larger truck option has grown from offering an engine that had no NOx or PM standards to meet to the current 6.7L Power Stroke in its Super Duty, which is able to meet a 0.20 g/bhp-hr NOx standard as well as a 0.01 g/bhp-hr PM standard (vs. 10.7 g/bhp-hr and 0.60 g/bhp-hr 30 years prior). Additionally, Ford’s current high output diesel offering turns out an incredible 500 hp and 1,200 lb-ft of torque while doing it. The 2023 F-450 XL model shown above is equipped with the ladder engine, and capable of towing 40,000 pounds.

Future Emissions

While the current crop of Power Stroke, Cummins and Duramax diesels are the cleanest (and most powerful) versions ever offered, they will soon have to meet an even stricter set of emissions standards. In 2027, a new, ultra-low NOx standard of 0.020 g/bhp-hr (vs. 0.20 g/bhp-hr currently) will go into effect. It remains to be seen exactly how Ford, Cummins and GM will make their engines adhere to the new regulation, but our expectation is that future versions of the Power Stroke, Cummins and Duramax will get there through the use of more advanced exhaust gas recirculation (EGR) and selective catalytic reduction (SCR) technology.

Current Holdup: Transmission Strength

Thanks to high-pressure common-rail injection, variable geometry turbochargers and modern electronics, diesel engine manufacturers have zero problem making their engines produce big horsepower and torque. However, downwind of those numbers there is often an automatic transmission living on the brink of its torque-harnessing capabilities—even in stock form. GM’s 10L1000 Allison and Ram’s 68RFE have significant weak points, and even the Aisin AS69RC found in high output Ram applications and Ford’s 10R140 have their shortcomings. Going forward, the only way the torque war will continue (or escalate) is if stronger transmissions are brought to market.

Why BEV Technology Won’t Kill Off Diesel

Although some in-roads have been made in the commercial BEV segment (think Tesla’s regional haul “Semi”), BEVs have yet to prove they have the ability to even remotely challenge diesel’s dominance in the pickup truck realm. Much of this revolves around range. Even when towing at a late-model diesel truck’s maximum gross combined weight rating (GCWR), between nine and 12 mpg is possible—or a range of roughly 350 miles, depending on the size of the tank (which varies slightly from brand to brand). From what we’ve seen in half-ton BEV testing, only half of that range (at best) would be achievable in a ¾-ton or larger truck. Under immense workloads, diesel maintains exceptional range while, at least for the time being, battery-electrics in this class of vehicles do not.

Detroit Is Still Investing In Diesel

The fact that The Big Three are still investing in the diesel ICE tells you everything you need to know about the next decade-plus of heavy-duty pickup trucks. Case in point, General Motors wouldn’t have recently invested nearly $1 billion in its DMAX engine operation if it wasn’t committed to offering a Duramax diesel-powered HD truck well into the future. The automaker’s engine component plant for the current 6.6L Duramax will be quadrupled in size, going from 250,000 square feet to 1.1 million, before all is said and done. That’s an incredible investment and one that says GM is playing the long game with its bread-and-butter HD pickup engine.

If The Duramax Isn’t Going Anywhere…

Then neither is Ford’s 6.7L Power Stroke or the 6.7L Cummins option in Ram heavy duties. In 2019, Ram debuted a brand-new, high output 6.7L Cummins for its fifth-gen trucks, complete with a compacted graphite iron block. In 2020, Ford released the revamped 6.7L Power Stroke V8—an engine that now packs Class 8-like, steel pistons. Since then, both of those power plants have been treated to significant torque increases, with Ford’s ’23 model year H.O. Power Stroke turning out an unprecedented 1,200 lb-ft. If OEMs, which plan ahead at least five-to-10 years in advance, thought the future of diesel looked bleak, you never would’ve seen these engines released.

What To Expect In The Next 5 To 7 Years

So what does the five-year forecast look like for diesel? We think that (in addition to seeing stronger transmissions) Ford’s 1,200 lb-ft of torque rating will be challenged and even surpassed by the competition. It may sound wild, but expect to see the 1,300 lb-ft threshold breached—and maybe even 1,400 lb-ft. In order to get there, a myriad of things could happen, but we suspect high injection pressure and steel pistons could be part of the engine recipes. As far as meeting tighter emissions, we think the OEM’s have that in the bag, too. As we alluded to earlier, they have room left over to improve on existing EGR and SCR systems.