Jeep Grand Cherokee 3.6L Pentastar V6 vs 5.7L Hemi V8: Real Fuel Economy
Choosing between the Pentastar V6 and the Hemi V8 for your Jeep Grand Cherokee often comes down to one big question: is the extra power worth the extra gas? While the EPA ratings give you a starting point, the real-world numbers can tell a more complete story.
TL;DR
For a current 2025 model, the 3.6L Pentastar V6 is rated at 19 MPG city / 26 MPG highway / 22 MPG combined. The 5.7L Hemi V8, now discontinued for most new Grand Cherokees, was rated at about 14 MPG city / 20 MPG highway for the 2014 model year. The V6 offers a significant real-world advantage, especially around town, with some older reviews showing the V8 averaging around 12.7 MPG in mixed driving and a 2005 model returning 14.5 L/100km (approx. 16 MPG) on the highway.
The Official Numbers (EPA Ratings)
The environmental protection agency (EPA) ratings provide a standardized way to compare these two engines.
3.6L Pentastar V6
- Horsepower: 293 HP
- Torque: 257 lb-ft
- Fuel Economy (city/highway/combined): 19 / 26 / 22 MPG
5.7L Hemi V8
Note: The Hemi V8 has been discontinued in the Grand Cherokee. The numbers below are from when it was offered in model years like 2014.
- Horsepower: 360 HP
- Torque: 390 lb-ft
- Fuel Economy (city/highway/combined): 14 / 20 / 17 MPG (combined) or 14 city / 20 highway
The official numbers show a clear lead for the V6. You can expect the V8 to consume more fuel, especially in stop-and-go city driving. The V6 offers a 5 MPG advantage in the city and a 6 MPG advantage on the highway, which can add up significantly over time.
Real-World Fuel Economy: What Owners Are Getting
Official ratings are one thing, but real-world driving conditions often paint a different picture. Here’s what some real-world tests and owner experiences have shown.
The V6 in the Real World
The Pentastar V6 is known for being a smooth and capable daily driver. While 22 MPG combined is the EPA estimate, many owners find the V6 delivers solid fuel economy for a vehicle this size. A 2012 review of the 3.6L V6 in a Chrysler 200 (a different, lighter vehicle) returned a real-world average of 26.2 MPG, but it’s important to note that this is from a car, not an SUV.
The V8: The Price of Power
The 5.7L Hemi V8 is all about the driving experience. It offers a “gruffer exhaust note” and “deep, low-down torque” that the V6 simply can’t match. That experience comes with a cost at the pump.
- A review of a 2014 Grand Cherokee Hemi averaged just 12.7 MPG during its test drive.
- A 2005 review of the 5.7L Hemi found it returned 14.5 L/100km (about 16 MPG) at highway cruising speeds, but this number could jump to 21-25 L/100km (9-11 MPG) in low-range or off-road driving.
- A 2008 Hemi V8 had an EPA combined rating of 17 MPG.
- These numbers suggest that while the Hemi’s cylinder-deactivation system (MDS) helps, it doesn’t close the fuel economy gap with the V6 in everyday driving.
Fact: The 5.7L Hemi V8 uses a cylinder-deactivation system (MDS) that shuts down four cylinders when cruising to save fuel. However, as the numbers show, it’s still significantly less efficient than the V6.
The Big Picture: Beyond the MPG Numbers
The decision isn’t just about MPG.
Towing Capability
If you plan on towing, the V8 has an advantage, though it might be smaller than you’d think. It can tow up to 7,200 lbs, while the Pentastar V6 is rated for up to 6,200 lbs .
It’s Not Just About the V8 Anymore
For the 2025 Grand Cherokee, Jeep has discontinued the 5.7L Hemi V8 in the U.S. The engine is now only available in the three-row Grand Cherokee L for the 2025 model year. The V8 is becoming harder to find new, making the Pentastar V6 the default choice for most buyers.
The Bottom Line: Which One Should You Choose?
- Choose the 3.6L Pentastar V6 if: Fuel economy is a priority for your daily commute or long highway drives. You’ll save money at the pump, and it still offers the power you need for most daily tasks. It’s the sensible, economical choice for a daily driver.
- Choose the 5.7L Hemi V8 if: You crave the extra power, the distinctive V8 sound, and the higher towing capacity (7,200 lbs vs. 6,200 lbs). Be prepared for a noticeable hit at the gas station, as real-world fuel economy will be significantly lower than the V6.
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