Hyliion’s Hybrid Diesel System – Upgrade your Class 8 truck

Hyliion introduced their 6X4HE Hybrid Diesel System that will take Class 8 trucks performance to the next level. Developed in partnership with Mesilla Valley Transportation, PAM Transport, and Ryder, Hylion 6X4HE will let you enjoy lower emissions, lower fuel costs and a better driver experience. 

According to the company, the system was able to provide these benefits that sum up to 30% fuel and emission savings because it uses hybrid electrification. The three technologies that provide these fuel savings are electric hybrid drive axles that contribute to 15% of the fuel savings, APU with 12%, and aerodynamics for the remaining 3% fuel savings.

“A hybrid system has many of the benefits of a fully electric truck, but you can bring it into your fleet now.” said Hyliion Chief Executive Officer Thomas Healy. “You don’t need to recharge our system. You don’t need to plug it in. You just put it on the truck and it’s a self-sustaining system. You’re not going to see 100% fuel savings like you would with electric, but you’re going to see that stepping stone of 30% savings by using hybrid technology, and you don’t have any of the infrastructure problems or those big up-front costs.”, he added.

Healy also explains that on the technology side, the company’s whole goal is to keep the diesel engine in its sweet spot. The company is looking at how hard the diesel engine is working. Is it downshifting? Is the engine revving up? Is it coasting and not consuming any fuel? Then the system’s algorithms will decide when to apply electric power or when to capture energy. 

“An example of this is if you’re climbing a hill, normally, the diesel engine would downshift and the RPMs would start climbing. You’d start consuming more fuel in order to maintain speed while climbing the hill. With our system, the goal is to not have the vehicle downshift so it stays in that higher gear, which causes the RPMs to stay lower and it to consume less fuel.”

“Electrification is the popular buzzword right now, and there’s a big push for it, but we feel that hybrid technology is what makes sense.”


Hylion 6X4HE was designed with the power of machine learning to boost fuel and emissions savings. The location of system components and interfaces were improved better serve the drivers and service personnel and also to optimize data communications and power distribution.

The intelligence algorithm of the system maximizes fuel economy by automatically determining precisely when to deploy captured energy. This also keeps the diesel engine in its most efficient operating range.

Photo Credit: Hyliion

Hyliion 6X4HE can be installed in any Class 8 trucks from any manufacturer because of its modular design that requires no driver training and allows for easy installation and simple servicing.

Battery Pack

With Hyliion’s battery technology, electric axle and climate control system will be provided by power in idle free scenarios.

Control Unit

Manage the power for optimal fuel savings and use an Intelligence Algorithm to look at the topography of your route.

Thermal Management System

Keeps the system at its optimal operating temperature. It also eliminates idle time for 2% fuel and emissions savings by providing climate control for the entire mandatory rest period

Electric Axle

Reduce the load on the engine on hills and during acceleration which delivers fuel and emissions savings for about 7-10% in rolling terrain and up to 15% in hilly terrain.

Co-Pilot Display

Gives the driver the ability to monitor the system’s real-time driving performance and manage the Climate Control System in idle free scenarios.


Deliver 3% fuel and emissions savings by significantly reducing air resistance at speed because of it’s comprehensive aerodynamics package.


Over-the-road and long haul trucking requires diesel. This is because the energy in diesel is 50 times more than even the leading Li-ion battery. This means using batteries would need for the truck to be charged twice a day and replace batteries every two years.

Photo Credit: Hyliion

Regenerative braking captures power when slowing down then electric power is applied when necessary to keep diesel engines at their most efficient RPM delivering hybrid fuel savings. The APU delivers 18,000 BTUs for 10 hours on a single charge by optimizing Hyliion’s cooling system and battery. The 6X4HE is also Shore Power enabled and electricity was provided in the cab by two outlets.

Photo Credit: Hyliion

“What we do is we take your conventional, diesel-powered truck and add on an electric axle and battery pack system,” Healy explains. “When the vehicle is slowing down or going downhill, we can capture all that wasted energy and store it in the battery pack for when the vehicle accelerates or goes uphill. Then we can take that energy and use it to help propel the vehicle forward. By doing that, the diesel engine doesn’t have to work as hard.”

Hyliion’s Climate Control includes the battery and motor Thermal Management System that delivers 12 hours of superior performance with an output of 20,000 BTUs, provides 10% fuel and emissions savings and increases driver satisfaction up to 95%. This feature does not take power from the truck’s AC and accessories so it won’t drain the 12 volt batteries.

Hyliion also focuses on the maintenance side of the Hybrid System design that only requires annual fluid changes every 300,000 miles. 

With all these features, the driver will have better experience on:

  • Automatic Operation
  • Over-The-Air Updates
  • Power Boost
  • Regen Breaking

Heavy duty trucks contribute more than 2 billion metric tons of greenhouse gases globally. If these trucks use the Hyliion hybrid diesel system, this can eliminate more than 690 million metric tons of greenhouse gases and save the industry nearly $60 billion.

“The fully electric trucks are a wonderful, ideal solution for short-haul, local delivery, where you can set up a recharging station at your warehouse and you can charge it up when it goes out for the day and when it gets back at night you can plug it back in,” Healy says. The way Healy sees it, building a sufficient network of charging stations across the U.S. for vehicles such as the Class 8 electric truck is going to take more than a decade.

Healy claims that the trucks that frequently traverse hilly terrain and by drivers who sleep in their trucks will see the greatest fuel savings and APU benefits. He also added that while Hyliion’s hybrid systems are only available in Class 8 applications at the moment, Hyliion are already working on bringing it to medium-duty trucks as well.

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