Trucks are where natural gas fuel actually goes. Refuse fleets, transit agencies, port drayage and regional tractors burn most of the CNG sold in the U.S., which is why 84% of public stations are marked for Class 8 access and why the big networks build at truck stops. A new 15-liter natural gas engine, the Cummins X15N, arrived in 2024 and put long-haul on the table for the first time.
Class 8 tractors
| Engine | Size / power | Where it goes |
|---|---|---|
| Cummins X15N | 15 L, up to 500 hp / 1,850 lb-ft | Freightliner Cascadia, Kenworth T680 and T880, Peterbilt 579 and 567. Long-haul and heavy regional. Launched 2024. |
| Cummins ISX12N | 11.9 L, up to 400 hp / 1,450 lb-ft | Same tractors, plus day cabs and vocational. Regional haul, drayage, tanker. The workhorse since 2018. |
| Cummins L9N | 8.9 L, up to 320 hp | Refuse trucks (Mack, Autocar, Peterbilt 520), transit buses (New Flyer, Gillig), medium-heavy vocational. |
| Cummins B6.7N | 6.7 L, up to 240 hp | School buses, shuttle buses, medium-duty box trucks. |
All of these are spark-ignition engines that run only on natural gas. They use the same maintenance intervals as their diesel siblings but different spark plugs, oil and filters, and they need a shop that understands the fuel system. The fuel is stored in Type 3 or Type 4 cylinders mounted behind the cab, along the frame rails, or on a roof-mounted rack; a full package adds roughly 1,000 to 2,000 pounds versus a diesel.
Refuse, transit and drayage
Refuse trucks were the first big adopter because they return to a yard every night, where a time-fill station tops them up on a slow overnight compressor, and because a natural gas engine is far quieter on a 5 a.m. residential route. Transit agencies followed for the same yard-fueling reason. Port drayage at Los Angeles and Long Beach adopted natural gas under clean-truck rules. All three run on private stations that never appear on public maps, which is why the DOE database has as many private natural gas sites as public ones.
Factory bi-fuel pickups and vans
- Ford F-150 (2014 to 2016), 5.0 L V8. A factory gaseous-fuel prep package (hardened valves and seats) for about $315, then a CNG or propane system from a Ford-qualified upfitter for roughly $7,500 to $9,500. Bi-fuel; the 26-gallon gasoline tank stays.
- Ford Super Duty F-250 to F-750 and Transit. The 7.3 L V8 and, earlier, the 6.2 L and 6.8 L engines carry the same prep package. Ford still lists it, which makes Super Duty the only current-model pickup you can order CNG-ready from the factory.
- Chevrolet Silverado and GMC Sierra 2500HD bi-fuel (2013 to 2016), 6.0 L V8. Built by GM's upfitter with a 17 GGE bed-mounted tank, about 650 miles of combined range. GM later offered CNG-capable engines on the 2500HD and 3500HD and on Express and Savana vans through its upfit program.
- Ram 2500 CNG (2013 to 2015), 5.7 L Hemi. The only pickup with the CNG system built on the assembly line: an 18.2 GGE tank in the bed plus an 8-gallon gasoline tank. Crew cab, long bed, mostly sold to fleets.
These trucks turn up used, often from utility or municipal fleets with high miles and good records. The same cylinder checks as any CNG vehicle apply; the conversion page has the inspection schedule.
What a truck driver should read on a station listing
- Class 8 OK means the DOE record marks the site for heavy-duty vehicles. Sites without it may be car-height canopies at a utility office.
- Quick-fill is what you want. A time-fill-only site is a fleet yard hose.
- 3,600 psi is the standard for current trucks. A 3,000 psi site gives a partial fill.
- Cards. Comdata, EFS, Fleet One, WEX, Voyager and network cards are listed per station. Most sites also take Visa and Mastercard.
- The corridor pages show these badges for every station along I-10, I-40, I-35, I-80, I-5 and I-95, in driving order with the longest gap on each.
FAQ
What natural gas engines are available in new Class 8 trucks?
Cummins builds the natural gas engines used by Freightliner, Kenworth and Peterbilt: the 11.9-liter ISX12N (up to 400 hp) and, since 2024, the 15-liter X15N (up to 500 hp), which was designed to match a diesel in long-haul duty. The 8.9-liter L9N and 6.7-liter B6.7N cover refuse, transit, vocational and medium-duty trucks.
How far does a CNG semi truck go on a fill?
It depends on the tank package. Back-of-cab and frame-rail cylinder packages hold roughly 100 to 175 diesel gallon equivalents, and a loaded tractor burns about 5 to 6 miles per DGE, so 500 to 900 miles between fills is typical.
Which pickups came from the factory with CNG?
Ford offered a gaseous-fuel prep package on the F-150 (2014 to 2016) and continues to offer it on Super Duty trucks with the 7.3-liter V8, with the CNG system installed by a Ford-qualified upfitter. GM sold a bi-fuel Silverado and Sierra 2500HD (2013 to 2016), and Ram sold a factory-built bi-fuel Ram 2500 CNG (2013 to 2015).
Are CNG stations built for trucks?
Most are. The DOE record for each station says which vehicle class it can serve, and about four in five public CNG stations are marked for heavy-duty. Sites hosted by truck stops and by networks such as Clean Energy, Love's and Trillium are laid out for tractor-trailers; some utility and municipal sites are not.