Volvo Group says it remains fully committed to internal combustion engine technology, and demonstrated it by showing off its new D17 diesel engine in Sweden.

In an event for North American journalists at Volvo’s home campus in Gothenburg, Sweden, waiting on a test track a few miles away was a cobalt blue, brand-new FH 16 tractor with an also-new D17 diesel engine mounted under the cab. So I was able to see first-hand what Volvo's vision for diesel-powered freight efficiency looks like. 

The D17 is the largest diesel engine ever put into a Volvo truck. And it’s the most powerful, too. The engine is available in three versions: 600 hp, 700 hp and the ultimate, 780 hp option. These engines churn out an incredible 2,212, 2,507 and 2,802 lb-ft of torque.

This modern diesel engine technology gives drivers faster engine response, improved driveability, maximum productivity and – yes – improved fuel economy, compared to the D16 diesel it replaces, according to Volvo.

A Method to the Madness

What’s going on here? Volvo is all about battery-electric and hydrogen fuel cell trucks these days, right? Why on a clean Earth would one of the OEMs leading the charge toward a zero-emission trucking industry be introducing a 780-hp diesel engine?

Volvo considers the D17 engine to be a clean, low-emissions, high-fuel economy option for diesel fleets running in Europe now. As such, the OEM sees the new engine as wholly in line with its zero-emission mission.

A new set of length and weight regulations for Class 8 trucks is now the law in Sweden. Under these new regulations, which went into effect on Dec. 1, 2023, it is now legal to run combination trailers totaling 113 feet (34.5 meters) in length and up to 100 tons (93 tonnes) GCW on mandated Swedish highways.

The Swedish government calculates that using these longer and heavier combinations can reduce energy consumption by up to 30% for individual vehicles and by 4% to 6% overall. These figures hold true for BEVs, hydrogen fuel cells and biofuel and diesel engines.

A more simplistic measurement, presented by Volvo, demonstrates that one 34.5-meter tractor-trailer can haul as much freight as two to three conventional tractor-trailer rigs, with equivalent reductions in NOx emissions and fuel consumption.

To date, these super combo tractor-trailers are only allowed on about 3,100 miles (5,000 kilometers) of the best, most modern Swedish highways. But the government is considering opening up additional stretches of highway in the future.

The Technology of Volvo's New D17 Diesel Engine

The D17 engine is a wonder of modern diesel technology. During a pre-drive briefing at the Volvo Test Track in Gothenburg, Lars Martesson, environmental and innovation director for the Volvo Group, noted that the new engine is equipped with a single efficient turbocharger to boost engine responsiveness.

Its designers also built upon Volvo’s highly successful and patented wave piston design to further optimize the D17’s combustion process. The result is a cleaner engine that actually provides more power and fewer emissions than the D16 engine it replaces.

A new injection system aids providing optimal fuel economy, while increased peak cylinder pressure enables high power output.

D17 engine brake power has been beefed up across the entire speed range, Martensson said. This enables fast gearshifts and results in less wear and tear on the brake pads and disc brakes, while being more efficient going downhill.

The D17 engine is certified to run on biodiesel in all power ratings. Additionally, the 700 hp version is also certified to run on 100% biodiesel (B100).

Surprisingly Smooth and Quiet

Driving the 780-hp FH16 was a surprisingly uneventful — and delightful — experience, despite the two long trailers lurking behind the tractor.

As a European model, the FH16 is a Class 8 cabover, of course. That means the interior is naturally smaller than a North American conventional cab. But the truck is incredibly comfortable and sports a completely modern dash with crisp, clear display graphics. The most critical vehicle control systems, such as the transmission selector switch and engine brake, are literally within fingertip reach. And all of the controls can be accessed confidently and quickly with little distraction from driving.

The truck was equipped with StoneRidge MirrorEye rear-view cameras. The system includes rear-view display screens mounted on the A-pillars. These screens can be configured to show various angles and viewpoints behind the truck.

I like the system on conventional tractor-trailers. But I found it extremely useful in tracking the two long, 34.5-meter trailers snaking behind me as I pulled out of the parking lot and out onto the track.

The D17 is remarkably quiet. It’s also one of the smoothest diesels I’ve ever driven. Throttle response, complemented by the quick-shifting I-Shift transmission, is instantaneous. The FH16 started moving forward without any strain or hesitation at all. If it weren’t for the MirrorEye viewscreens on either side of the cab, you’d never know the truck was pulling 81 tons of cargo behind it.

The entrance to the Gothenburg track is via a 5% upgrade with a 9% downslope. Here I thought the D17 would surely strain a bit — especially at such a low starting speed. But the FH16 lugged right up the grade effortlessly without a single downshift.

Likewise, on the downslope. The integrated Volvo engine brake easily kept my momentum in check without the need to get on the service brakes at all. With my foot back on the throttle, the rig accelerated quickly to 40 kph as I navigated through a few curves, and even flirted with 60 kph on the brief straightaway section of track.

To be honest, the truck drove so smoothly, was so easy to control, and so quiet, the drive was largely uneventful.

What Does the D17 Technology Mean for North American Trucking?

Volvo's impressive D17 won’t be hitting North American shores any time soon. It’s a low-volume engine, and Volvo executives told me they don’t see a market for it in Canada or the U.S. currently.

But is the “super combination” a freight-efficiency solution that could work on long-haul routes in North America? It’s such a counterintuitive approach to lower-emission trucking, my hunch is it would be a hard sell to unknowledgeable environmentalists on this side of the Atlantic.

But this approach makes a lot of sense to me. It also makes sense to HDT Equipment Editor Jim Park, who wrote about longer combinations and freight efficiency a few years ago: Why Waste Time on Platooning When LCVs are More Efficient?

And I think this Swedish experiment in longer, heavier tractor-trailers is worth keeping an eye on. Perhaps in a few years, it will make sense to attempt on this side of The Pond.