New Clean Energy RNG Demo Truck Program Features Cummins X15N in Latest Cascadia
Clean Energy Fuels is launching a second heavy-duty natural-gas truck demo program featuring the Cummins X15N, this time in the Gen 5 Freightliner Cascadia.

Clean Energy's second demo truck program will allow trucking fleets to try out the Cummins X15N natural gas engine in their own operations.
Photo: Clean Energy Fuels
Clean Energy Fuels is launching a second heavy-duty natural-gas truck demo program featuring the Cummins X15N engine.
Clean Energy’s demo truck program will give heavy-duty trucking fleets the opportunity to experience the capabilities of the Freightliner Cascadia Gen 5 equipped with the X15N. Participating carriers will be able to fuel at Clean Energy’s network of renewable natural gas stations nationwide, integrating low-carbon fueling into their own fleet operations.
The Cummins X15N engine is designed to run on RNG, a biogenic fuel derived from organic waste such as dairy manure. Fleets fueling with RNG can reduce emissions by more than 300%, according to Clean Energy, achieving negative carbon-intensity results while spending less per gallon of fuel.
The company said major motor carriers such as Walmart, Amazon, UPS, FedEx, Werner, Knight Swift, Food Express, Cemex and Mullen Group having placed orders for the new engine.
The demo truck will travel through key freight corridors in California, Texas, Arizona, Illinois, Ohio, Michigan, Pennsylvania, Florida, and other states, allowing large and mid-sized fleets to try and test the engine’s capabilities in real-world conditions.
The X15N Freightliner demo truck program is expected to run through 2028 or longer, as demand and interest are expected to grow.
Why So Much Interest in Cummins’ X15N natural gas engine?
Although natural-gas engines for trucks have been available for years, previous models, including Cummins’ previous 12-liter ISX12N, just didn’t have the power needed for many heavy-duty trucking operations requiring higher torque.
Clean Energy’s first X15N demo truck program, featuring a Peterbilt Model 579 day cab tractor, was launched last year.
The first demo truck has been praised by fleets who have operated it for the engine’s smooth handling through different terrains, impressive torque, per-gallon savings running on RNG, and fuel efficiency, according to a Clean Energy news release.
The new truck will be showcased at the American Trucking Associations’ Management Conference & Exhibition in San Diego from October 25–28. Attendees will have an exclusive preview before the program launches with its debut fleet partner, Airgas, a distributor of industrial, medical and specialty gases.
Clean Energy: X15N and RNG a ‘Clear Winner’
“Through one of the most tumultuous times in the history of the freight industry with evolving regulatory changes, impacts of tariffs, and overall economic uncertainty, the X15N/RNG solution has come out a clear winner for both carriers and shippers,” said Chad Lindholm, senior vice president at Clean Energy, in a release.
“The Cummins X15N truly is a game-changer, providing equivalent power and torque as its diesel equivalent, yet allowing fleets to claim significant carbon and NOx emission reductions with a fuel that is priced at a big discount to diesel," he continued.
“The reason we have a waiting list to test our demo trucks is because despite regulatory easing, operators of fleets and their customers continue to want to have the cleanest trucks. Viable electric and fuel cell options are years and years from becoming an affordable reality. RNG is the only solution that is here today, affordable, and clean.”
More Fuel Smarts

Cummins Adjusts 2027 Engine Rollout After EPA Proposal
The engine maker will gradually introduce its new Model Year 2027 diesel engines while continuing to offer current models during the transition, citing the EPA's proposed emissions rule changes.
Read More →
EPA Proposal Could Ease 2027 Truck Costs and Buying Uncertainty
The proposal doesn't change the tougher NOx standard, but it would revise key implementation requirements that manufacturers say have driven up costs and complicated fleet purchasing decisions.
Read More →
Cummins, Paccar Ease DEF Derates After EPA Guidance
Updated diesel engine software gives truck operators more time to address emissions-system issues while staying compliant with EPA emissions standards.
Read More →
Maintenance in the Messy Middle Part 3: Biodiesel
Biodiesel can reduce emissions, improve fuel-system lubricity and use existing diesel infrastructure. But NACFE’s Messy Middle maintenance report says fleets must actively manage storage, cold-weather operation, filters and oil drain intervals to avoid problems.
Read More →
Enhance Fleet Performance with High-Efficiency Auxiliary Power Units
Drive sustainable cost savings while increasing driver comfort during short- and long-haul logistics operations.
Read More →
Maintenance in the ‘Messy Middle’ Part 2: Renewable Diesel Fuel
NACFE's latest Messy Middle Powertrain Service & Maintenance report says renewable diesel gives fleets an opportunity to reduce carbon emissions without changing trucks, fueling infrastructure or maintenance practices. But technicians still need to understand several important operational differences.
Read More →
The Diesel Engine Enters NACFE’s ‘Messy Middle’
NACFE’s new Messy Middle Powertrain Service & Maintenance report says keeping modern diesel engines running now depends as much on software, diagnostics and data as traditional mechanical service.
Read More →
DTNA Software Update Gives Truckers More Time Before DEF Derates Take Effect
The changes reflect EPA guidance aimed at reducing downtime caused by emissions-system faults while maintaining compliance requirements.
Read More →
New Agentic Predictive Maintenance Report Demonstrates How Degraded Aftertreatment Systems Waste Fuel
Questar analyzed a large mixed-class fleet and discovered it was wasting as much as $30 in fuel per vehicle, per day, because of mechanically degraded aftertreatment systems.
Read More →
New York City's Microhub Project is Delivering Results
Trucking, last-mile delivery companies, and environmental advocates like what they are seeing so far with New York's microhub program.
Read More →
