Ram 2500 6.4 Hemi Specs and MPG by Year 2014 to 2026

The Ram 2500 6.4 Hemi has made 410 horsepower and 429 lb-ft of torque for most of its production run, dropping to 405 horsepower starting with the 2025 model year while torque held steady at 429 lb-ft. That is easy to miss on a spec sheet, and it is only one of two real changes this engine has seen since 2014.

The bigger shift happened in 2019, when Ram swapped the six-speed automatic for an eight-speed unit that changed how the engine feels in daily driving and under load. This guide breaks down exactly what changed, when it changed, and what it means for real world MPG, towing capacity, and buying a used Ram 2500 6.4 Hemi today.

6.4 Hemi Horsepower and Torque by Year

The 6.4 Hemi’s horsepower rating has changed exactly once in over a decade of production. Ram’s own engine performance pages list 405 horsepower and 429 lb-ft of torque for the current model year, a 5 horsepower reduction from the 410 hp figure that held from 2014 through 2024.

Torque staying flat while horsepower dipped slightly points to a recalibration rather than a mechanical downgrade. Nothing about the block, heads, or displacement changed between these two eras.

Transmission Change From 6 Speed to 8 Speed in 2019

The transmission behind the 6.4 Hemi changed more than the engine itself ever did. From 2014 through 2018, the 6.4 Hemi was paired exclusively with the 66RFE six-speed automatic. Starting in 2019, Ram switched to the ZF 8HP75-LCV eight-speed automatic, a longitudinally mounted unit built specifically for four-wheel-drive heavy-duty applications.

Owners who have driven both generations consistently point to the 8-speed as the bigger upgrade. The 6-speed’s wide gear spacing meant the engine spent more time at high RPM under load, while the 8-speed holds a usable gear longer and shifts more smoothly whether the truck is empty or towing.

If you are comparing a 2018 and a 2019 Ram 2500 6.4 Hemi side by side, the transmission difference will be far more noticeable day to day than the identical horsepower rating on paper. Owners researching a used truck should also check for known 6.4 Hemi transmission problems by model year before buying, since the two transmission generations have different failure patterns.

Real World MPG by Year and Driving Condition

The EPA does not publish fuel economy ratings for the Ram 2500, since its Gross Vehicle Weight Rating sits above the 8,500 lb threshold the agency uses for testing. Every MPG figure below comes from independent testing and owner-reported data rather than a window sticker.

Real world fuel economy for the 6.4 Hemi typically falls into these ranges:

• City driving: 10 to 14 mpg
• Highway cruising at 65 to 70 mph: 13 to 18 mpg
• Combined average: 11 to 15 mpg
• Towing a trailer: 7 to 9 mpg

Owners on ramforum.com report similar numbers, with hand-calculated highway figures commonly landing in the 15 to 18 mpg range and city driving closer to 12 to 13 mpg. Rear axle ratio matters here too. Trucks with 3.73 gears tend to see slightly better highway mileage than those with the 4.10 gears, which are geared more for towing than fuel economy.

The 8-speed transmission introduced in 2019 gets modest credit for improved highway mileage compared to 2014-2018 trucks, mostly because it keeps the engine in a more efficient RPM range at cruising speed.

Towing and Payload Capacity by Year

Towing capacity for the 6.4 Hemi ranges from roughly 14,370 lbs up to 17,840 lbs depending on cab style, bed length, axle ratio, and whether the truck is 4×2 or 4×4. Payload capacity ranges from about 4,010 lbs up to 4,580 lbs using the same variables.

These are configuration-dependent maximums rather than a single number that applies to every 6.4 Hemi truck. A regular cab 4×2 with 4.10 gears will tow more than a crew cab 4×4 with the same engine. For the full breakdown by cab, bed, and axle configuration, the Ram towing capacity chart by year covers every combination in detail.

6.4 Hemi vs 6.7 Cummins Specs Side by Side

The tradeoff between these two engines comes down to one sentence: the Hemi wins on payload and upfront cost, the Cummins wins on towing and highway mpg.

• 6.4 Hemi: 405 to 410 hp, 429 lb-ft of torque, up to 4,580 lbs payload, up to 17,840 lbs towing
• 6.7 Cummins: 370 to 430 hp depending on year, up to 1,075 lb-ft of torque, up to 20,000 lbs towing, lower payload at roughly 3,150 to 3,990 lbs

The Cummins also tends to average better highway MPG despite its extra weight, largely because diesel engines run more efficiently at highway cruising speeds. For a full breakdown of the diesel side of that comparison, see the 6.7 Cummins engine specs for the Ram 2500.

Which Model Years Are the Better Used Buy

For most used truck shoppers, a 2019 or newer 6.4 Hemi is the safer pick. The 8-speed transmission is more refined under load, holds up slightly better in daily driving, and gives a small MPG edge over the 2014-2018 trucks.

That does not mean a 2014-2018 truck is a bad buy. The 6.4 Hemi engine itself did not change during this window, and plenty of 6-speed trucks have covered well over 150,000 miles without major issues. For a deeper look at long-term reliability across every model year, the Ram 2500 6.4 Hemi specs and reliability guide covers common problems by year in more detail.

The 6.4 Hemi Has Only Changed Twice Since 2014

Across more than a decade of production, the Ram 2500 6.4 Hemi has really only changed in two meaningful ways: the 2019 switch to an 8-speed transmission and the 2025 horsepower adjustment from 410 to 405 hp. MPG, towing, and payload have stayed remarkably consistent the whole way through.

For most Ram 2500 buyers who tow occasionally rather than daily, the 6.4 Hemi specs and mpg numbers here make it a practical choice regardless of which side of 2019 the truck falls on. If heavy, frequent towing is the priority, the Cummins numbers above are worth weighing before you decide.

Frequently Asked Questions

What year did the Ram 2500 6.4 Hemi get an 8 speed transmission?

The 6.4 Hemi switched from the 66RFE six-speed to the ZF 8HP75-LCV eight-speed automatic starting with the 2019 model year. This is considered the biggest real-world change to the engine’s drivability since its 2014 introduction.

Did the Ram 2500 6.4 Hemi horsepower change in 2025?

Yes, horsepower dropped from 410 hp to 405 hp starting with the 2025 model year. Torque stayed the same at 429 lb-ft, suggesting a tuning recalibration rather than a mechanical change.

What real world mpg does the Ram 2500 6.4 Hemi get?

Owners typically report 10 to 14 mpg in the city and 13 to 18 mpg on the highway, with combined averages around 11 to 15 mpg. Towing drops that to roughly 7 to 9 mpg depending on trailer weight and axle ratio.

How much can a Ram 2500 6.4 Hemi tow?

Towing capacity ranges from about 14,370 lbs to 17,840 lbs depending on cab style, bed length, axle ratio, and drivetrain. Check the specific configuration on the driver’s door jamb sticker for the exact rating on any individual truck.

Is the 6.4 Hemi or 6.7 Cummins better for a Ram 2500?

The 6.4 Hemi offers higher payload capacity and a lower purchase price, while the 6.7 Cummins offers more towing capacity and better highway mpg. The right choice depends on whether payload or heavy towing matters more for your use case.