This is the fork in the road on every heavy duty order sheet, and the honest answer is that it depends on your duty cycle rather than on which engine is better. The 6.7 litre Cummins makes 1,075 lb ft and pulls the 2026 Ram 2500 up to 20,000 lb. The 6.4 litre HEMI makes 429 lb ft, pulls up to 17,740 lb, and carries more weight in the box than the diesel can. Both are on the lot in our new Ram 2500 inventory right now. What follows is the conversation we have across the desk two or three times a week, written down.

Key Takeaways

• The Cummins wins on pulling, and it is not close. 430 horsepower and 1,075 lb ft against 429 lb ft for the HEMI, and up to 20,000 lb of towing against 17,740 lb.
• The HEMI wins on payload. Up to 3,930 lb against 3,600 lb for the Cummins on the 2500. The diesel is heavy iron and every pound of it comes off your load allowance.
• The HEMI wins on cost of ownership. Lower purchase price, cheaper oil changes, no diesel exhaust fluid, no fuel filter service interval, and a simpler emissions system.
• Neither engine has a published fuel consumption rating in Canada. Heavy duty pickups over 3,856 kg gross vehicle weight rating with a long box are exempt from federal testing, so anyone quoting you an official L/100 km figure for either one is making it up.
• The deciding question is how often you are loaded. Pulling heavy most weeks points to the Cummins. Hauling in the box, short trips, or a truck that sits for stretches points to the HEMI.

The Two Engines, Straight Up

For 2026 the heavy duty lineup is down to two engines. There is no standard output diesel in the 2026 announcement, so the choice is genuinely binary.

6.7 litre Cummins High Output turbo diesel inline six. 430 horsepower and 1,075 lb ft, paired exclusively with the TorqueFlite HD eight speed automatic. Ram lists that torque figure as best in class available base diesel torque. On the Ram 2500 it is rated up to 20,000 lb maximum towing and up to 3,600 lb maximum payload.

6.4 litre HEMI V8. Just over 400 horsepower and 429 lb ft, with an eight speed automatic, cylinder deactivation and variable cam timing. On the Ram 2500 it is rated up to 17,740 lb maximum towing and up to 3,930 lb maximum payload.

Those are maximum available ratings for specific configurations. Cab, box, drive, axle ratio and hitch type all move the real number, which is why we always pull the exact figures off a VIN before anybody buys a trailer. If you are still deciding how much truck you need, the Ram 2500 versus Ram 3500 comparison covers the step up, and the Ram 1500 versus Ram 2500 comparison covers the step down for anyone wondering whether a half ton would have done the job.

Where the Cummins Genuinely Wins

Torque where you actually use it. 1,075 lb ft is not a bragging number, it is a driving experience. The diesel makes its shove low in the rev range, which means a heavy trailer moves off a gravel approach without drama and a long grade does not require a downshift and a lot of noise. If you have pulled the same load with both, you already know the difference and no spec sheet captures it.

The exhaust brake. This is the diesel advantage nobody puts on a comparison chart and everybody notices on the road. Descending a grade with 15,000 lb behind you on engine braking instead of on the service brakes is safer, calmer and easier on the truck. For anyone towing regularly in hilly country or through mountains on a holiday run, this alone can settle the argument.

Range. A diesel covering distance under load simply goes further between stops, and on a long haul that turns into fewer stops and less schedule.

Durability under sustained load. These engines are built for continuous heavy work, and the ones that are used that way go a very long way. That reputation was earned in the field, not in marketing.

Where the HEMI Genuinely Wins

Payload. Up to 3,930 lb against 3,600 lb. That 330 lb swing decides more purchases than people expect, because the pin weight of a fifth wheel plus fuel, passengers, hitch hardware and a loaded toolbox eats a payload allowance fast. If your load lives in the box rather than behind the hitch, the gas truck is the more capable truck.

Cost to buy. The Cummins carries a significant upfront premium. We will not print a number here because option pricing and incentives change constantly, but it is the largest single line item difference between two otherwise identical trucks, and it is the number to start your math with. Ask us for the current figure on the exact configuration you are looking at, or run it through the finance application and we will show you both side by side.

Cost to run. No diesel exhaust fluid to buy or refill. No diesel fuel filter service interval. Smaller and cheaper oil changes. A simpler emissions system with fewer parts to age out. Over ten years of ordinary use these add up, and for a truck that is not working hard they can add up to more than the fuel difference.

Cold weather simplicity. A gas engine starts at 35 below without a plug in, without winter fuel worries, and without a long warm up before it will make heat. Anyone who has spent a January morning waiting for a diesel to come up to temperature in a farmyard understands why this belongs on the list.

Short trip duty. A modern diesel wants to run hot and run long. A truck that does ten minute trips into town and then sits is not giving the emissions system what it needs, and that is where diesel owners run into the most frustration.

The Fuel Question Nobody Answers Honestly

Here is something worth knowing before you read another comparison page.

There is no official fuel consumption rating for either engine in Canada. Natural Resources Canada does not require manufacturers to submit fuel consumption data for pickup trucks with a gross vehicle weight rating over 3,856 kg and a box of 183 cm or more, which covers the heavy duty lineup. That is why you will not find a Ram 2500 in the federal ratings tables or on an EnerGuide label, and it is why any site quoting you a precise L/100 km figure for a 2500 is quoting something they invented.

What we can tell you from watching these trucks come back through our bays is the shape of it, not a number. Empty and around town the difference between the two is smaller than most buyers assume. Loaded and on the highway the diesel opens a real gap. That is exactly why duty cycle, not fuel price, is the right basis for the decision. If you want a number for your own truck, keep a fuel log for a season. That is the only figure that is actually yours.

Running Either One in Manitoba

If you go diesel, three things are not optional out here.

Plug it in. A block heater is not a luxury in a Manitoba January, it is how you get an easy start and a truck that makes heat before you reach the highway.

Respect the fuel. Winter blended diesel and a fuel system in good order are what keep you out of trouble in a cold snap. Our guide on the Cummins fuel filter change interval covers the service side.

Keep DEF topped up and stored properly. Diesel exhaust fluid freezes and it has a shelf life. The truck will manage a frozen tank on its own, but a jug that sat in an unheated shed all summer is a different story. Our Cummins DEF guide has the full rundown.

If you go gas, the maintenance is ordinary and the winter routine is short. That is the whole point of it.

Either way, every new 2026 and 2027 Ram 2500 bought at retail in Canada carries Ram's 10 year or 160,000 kilometre powertrain limited warranty, whichever comes first, covering the engine, transmission, transfer case, driveshafts, differentials and axles. It applies to both engines equally, it is not available on fleet purchases, and it is non transferable, so it belongs to the original retail purchaser or lessee. That coverage takes a lot of the fear out of the diesel decision for a buyer who was worried about a big repair in year eight.

So Which One Should You Buy

Buy the Cummins if you pull heavy most weeks, your trailer is a fifth wheel or a big deck, you cover real distance loaded, you tow in hills or mountains where the exhaust brake earns its money, or you keep trucks a very long time and work them hard the whole way.

Buy the 6.4 litre HEMI if your weight rides in the box, your towing is occasional or moderate, your trips are short, the truck sits for stretches, or the upfront and running cost difference matters more to you than the last 2,260 lb of tow rating.

The mistake we see most often is a buyer taking the diesel because it is the serious choice, then running it on short trips with an empty box. That truck costs more to buy, more to service, and never gets to do the thing it is good at. The opposite mistake, taking the gas engine and then discovering the trailer is at the limit of it every single weekend, is less common but more frustrating.

Tell us what you actually pull, how often, and how far. That conversation takes ten minutes and it has saved a lot of people a lot of money. Our service department also sees both engines all year, so if you want the unvarnished version of what each one costs to keep on the road out here, ask them.

FAQs

Should I get a diesel or gas Ram 2500?

Diesel if you tow heavy regularly, cover distance loaded, or want the exhaust brake. Gas if your weight is in the box, your towing is occasional, your trips are short, or the lower purchase and running cost matters more than maximum tow rating.

How much more does the Cummins tow than the 6.4 HEMI?

On the 2026 Ram 2500, up to 20,000 lb with the Cummins against up to 17,740 lb with the HEMI, a difference of 2,260 lb at the maximums. Your specific truck's ratings depend on its configuration.

Does the gas Ram 2500 carry more payload than the diesel?

Yes. Up to 3,930 lb with the 6.4 litre HEMI against up to 3,600 lb with the Cummins, because the diesel engine weighs considerably more and that weight comes off the payload allowance.

What is the fuel economy of a Ram 2500?

There is no official rating. Natural Resources Canada does not require fuel consumption data for pickups over 3,856 kg gross vehicle weight rating with a long box, so heavy duty trucks do not appear in the federal ratings or on an EnerGuide label. Any precise figure you see quoted for a 2500 is not an official one.

Is the Cummins worth the extra money?

It is if you use it. Heavy regular towing, long loaded runs and hilly terrain justify it comfortably. Light duty, short trips and a truck that mostly hauls in the box do not, and in that case the HEMI is both the cheaper and the more capable choice on payload.

Does the diesel need special care in a Manitoba winter?

Yes. Plug in the block heater, run winter blended fuel, keep the fuel filters on schedule and keep diesel exhaust fluid topped up and stored somewhere it will not sit for a year. None of it is difficult, but none of it is optional either.

The Bottom Line

The Cummins is the better engine for pulling and the HEMI is the better engine for hauling, buying and running. That is the honest scorecard, and it is why we ask about your duty cycle before we ask about your budget. Neither one is the wrong truck. The wrong truck is the one chosen because it sounded more serious on a Saturday morning. Come tell us what you actually do with a truck and we will match the engine to the job. Start with the new Ram 2500 inventory and we will go from there.

Tyler Dunn, Dunn Ram Trucks, Portage la Prairie