How many miles per gallon does a 2003 Dodge Ram 2500 5.9 Cummins get?
Typically, a 2003 Dodge Ram 2500 with the 5.9 Cummins diesel averages roughly 15–20 miles per gallon, depending on configuration and driving habits. Highway miles tend to be higher than city driving, and heavier payloads or four-wheel drive generally lower overall efficiency.
Context and what to expect
The 5.9 Cummins is a robust, torquey inline-six that delivers strong pulling power, which can come at the expense of economy when the truck is loaded or driven aggressively. The Ram 2500's weight, drivetrain (2WD vs 4x4), and whether it uses a manual or automatic transmission are the main levers that determine real-world MPG. Because official EPA figures from that era were often not published for every configuration, most owners rely on real-world ranges observed over mixed driving.
Estimated MPG ranges by drivetrain and transmission (stock, unmodified):
- 2WD with manual transmission (NV4500): combined roughly 16–18 mpg; highway around 18–21 mpg.
- 2WD with automatic transmission (A518/A46RE): combined roughly 15–17 mpg; highway around 18–20 mpg.
- 4x4 with manual transmission: combined roughly 15–17 mpg; highway around 17–19 mpg.
- 4x4 with automatic transmission: combined roughly 14–16 mpg; highway around 17–19 mpg.
In real-world mix, these figures can vary based on payload, terrain, and driving style. Highway cruising at steady speeds typically yields better numbers than stop-and-go city driving, and payload or towing can noticeably reduce MPG.
Factors that influence fuel economy
Several variables determine the actual fuel economy you’ll experience with a 2003 Ram 2500 5.9 Cummins. Weight, aerodynamics, and drivetrain configuration play major roles, along with how well the engine and related systems are maintained.
Key factors that influence MPG on the 2003 Ram 2500 5.9 Cummins:
- Drivetrain and transmission: 2WD generally offers higher mileage than 4x4; manual vs automatic can also shift efficiency depending on gearing and shift points.
- Engine condition and maintenance: clean air filters, proper fuel filtration, and regular oil changes help sustain efficiency.
- Weight and payload: heavier loads reduce fuel economy; removing unnecessary accessories can help.
- Tire condition and pressure: underinflated tires increase rolling resistance and reduce MPG.
- Driving style and conditions: smooth acceleration, steady speeds, and prudent braking improve overall efficiency; heavy towing or mountainous terrain lowers MPG.
Overall, expect a broad band of MPG depending on configuration and usage. A typical combined range for most owners sits around the mid-teens to high-teens, with higher highway numbers when the truck is light and driven efficiently.
Tips to maximize fuel economy
Small, practical changes can help squeeze a few more miles per gallon out of a 2003 Ram 2500 with a 5.9 Cummins, especially on long trips or frequent highway driving.
Tips to improve MPG on this truck:
- Keep tires inflated to the manufacturer’s recommended pressure to reduce rolling resistance.
- Perform regular maintenance: replace air and fuel filters on schedule, use quality diesel, and ensure injectors are clean and functioning properly.
- Use the correct engine oil and follow lubrication intervals; poor lubrication can increase friction and reduce efficiency.
- Minimize payload and aerodynamic drag: remove unnecessary racks or addons that increase air resistance.
- Drive with a steady throttle and use cruise control on highways when appropriate; avoid rapid acceleration and heavy braking.
- Plan efficient routes to reduce idling and stop-and-go driving; warm up the engine efficiently and avoid extended idling when possible.
These practices won't turn a rugged diesel pickup into a compact economy car, but they can help achieve a few more miles per gallon on long trips and reduce operating costs over time.
Summary
The 2003 Dodge Ram 2500 with a 5.9 Cummins diesel typically delivers about 15–20 mpg in mixed driving, with higher highway figures and lower city figures. Real-world mileage depends on drivetrain, transmission, payload, and maintenance, and careful driving and regular servicing can improve efficiency modestly. For buyers or current owners, understanding these ranges helps set realistic expectations and identify opportunities to maximize fuel economy.
