The connection between a Honda Civic Hybrid and a Class 8 truck may not be apparent to most, but it was a no-brainer for Thomas Healy, founder and chief executive of Hyliion Inc.

That Honda was Healy’s first car. The components that make hybrids work – electric motors, regenerative braking, batteries and operating software – are all ingredients in the electric drive axles his company develops.

Hyliion, founded when Healy left Carnegie Mellon University in 2015, is marketing its axles after several years of development and testing.

The Hyliion system takes up less room, weighs and costs less than a full hybrid-electric powertrain. (Image: Hyliion Inc.)

The company’s system, dubbed the 6x4HE, replaces the rearmost axle in tractors with either single- or double-drive axles. It provides electric boost for acceleration and hill climbing, reducing demand on the truck’s internal combustion engine. It also provides electricity for auxiliary power units, or APUs, so the truck doesn’t have to be kept idling.

The system can be installed as a retrofit or at a pre-delivery inspection or modification center alongside a a manufacturer’s assembly line, Healy said. It’s lighter and less expensive and takes up less real estate on the tractor compared with a full hybrid powertrain.

‘Intriguing System’

Healy, who turned 26 this year, claims the Hyliion system, with e-axle, APU power and aero improvements, can produce fuel savings of up to 30 percent for Class 8 rigs. With fuel savings come corresponding drops in emissions and truck operating costs, which can lead to a rapid payback of the additional cost of the hybrid system.

The pitch makes sense if Healy can back it up with data from Hyliion’s ongoing field tests.

“A reasonably affordable retrofit solution that cuts [fuel] costs by 30 percent is certainly appealing,” Sam Abuelsamid, a transportation analyst with Navigant Research, told

While Healy sees the Hyliion system as ideal for over-the-road tractors, some analysts think it has more limited applications, at least initially.

“It is a unique, intriguing system,” Steve Tam, vice president of ACT Research, told “But it is a very specialized solution with fairly narrow appeal.

“With today’s fuel costs, there aren’t a whole lot of folks clamoring for non-mainstream solutions to improve fuel efficiency,” Tam said.

Because the system depends on regenerative braking for its electrical power, using it on trucks dedicated to shorter routes with lots of stop-and-go driving could be “a more appealing solution,” said Abuelsamid. He sees hybrid axles as a “bridge technology” to help fleets cut fuel costs and emissions until advances in battery and charging technology make fully electric powertrains feasible.

Testing Brings Improvements

Hyliion is marketing the system for all types of heavy trucks. Much of its initial testing was in the long-haul segment, although on-road tests are being conducted with trucks doing short-haul and day-trip duty.

Early feedback from the testing fleets has led to updates and refinements to the battery cooling system and the software that controls regenerative braking and energy release logic and the APU, particularly its air-conditioning and heating functions, Healy told

One tester, PAM Transport Inc., hasn’t been able to verify fuel savings yet, said Paul Petit, vice president of maintenance for the Arkansas-based trucking firm. “We are still in the middle of the test,” Petit told

Drivers who’ve used the single Hyliion-equipped tractor in PAM’s fleet have reported, though, that the APU works well, pulling sufficient electricity from the Hyliion battery to run without power failures or other issues, he said.

The APU, designed to operate up to 10 hours on a single charge, can account for up to 40 percent of the Hyliion system’s claimed fuel savings, Healy said.

Hyliion says rear-wheel hub covers and gap-closure panels can deliver up to 3 percent fuel savings as part of its package. (Photo: Hyliion)

The drive axle itself provides about half the savings. Aerodynamics improvements – full wheel covers and wind deflectors – can account for up to 10 percent.

Ryder Systems, another of the firms testing the Hyliion axle, said it is too early in the project to have meaningful data, according to a spokesperson. The third tester – New Mexico-based Mesilla Valley Transportation – didn’t respond to’s request for comment.

Financial Backing

Even without hard data for independent tests, Hyliion has raised more than $30 million in funding from a number of green energy and new technology investors including Colle Capital Partners in Boston, Florida’s Axioma Ventures and New Era Capital Partners, of Tel Aviv.

Japanese financial conglomerate Sumitomo Corp. and FJ Management, a minority shareholder in the the Pilot Flying J truck stop chain, also have provided funding for the start-up.

Hyliion also has just launched a Series B financing round aimed at gathering an addition $20 million to $30 million, Healy said.

The company, which recently relocated from Pittsburgh to Austin, Texas, isn’t yet identifying its retail customers, but Healy says the company is installing its hybrid axles for several major fleets.

Commercial Orders

The initial orders are small, “five units or so,” Healy said. But they represent the first commercial validation of the idea developed in a university engineering class.

Healy, raised in the Boston area, has been an amateur race car driver since starting with go-karts when he was 8 years old. Throughout, he said, “I was exposed to the big rigs that hauled our cars.”

When he started driving his Honda hybrid and marveling at the fuel savings the system provided, “I wondered why trucks didn’t have the same technology,” he said.

He developed the e-axle concept with several classmates at Carnegie Mellon, dropping out of his post-grad program in 2015 to start Hyliion. Though his classmates were part of the early development, they aren’t part of the company now, he said.

Tractors Here, Trailers There

Initially, Healy envisioned and tested the e-axle as an add-on for the trailers that semis haul. But in the U.S., where trailers outnumber tractors and are often leased and swapped among fleets, he determined that it made more sense to put the e-axle directly on the tractor.

In Europe, fleets own their own trailers, so Hyliion aims to expand into that market with a trailer-mounted axle once its North American business is up and running, Healy said.

Hyliion hopes “to be looking at the international market in the not-too-distant future,” he said.

Transportation components developer and supplier Robert Bosch LLC has the same idea and in August announced its intent to develop a trailer-mounted e-axle hybrid system for the European market. Bosch also is developing the e-axle for Nikola Motor Co.’s fuel cell electric truck.

Healy doesn’t see Bosch as competition, however, but rather as a potential customer. There’s no deal on the table, “but we’ve had a number of talks with them,” he told

New Avenues

The company acquired a small battery-development firm from Gentherm Inc. earlier this year to bring its battery supply in-house. The Irvine, Calif., battery unit has sufficient capacity to allow Hyliion to build battery packs for others, “so we’re exploring going beyond just making batteries for our own products,” Healy said.

For now, though, Hyliion “has so much work ahead of us just to roll out the hybrid technology,” he said. “We are going to be focused on that, and there’s enough market to keep us going for a long time.”