You might have heard that the 2025 Ram 1500 is ditching the Hemi V8. The truck maker is putting a twin-turbo inline-six in its place, and the high-output version is mighty stout with 540 horsepower and 521 lb-ft of torque. Well, the team at 5th Gen Rams got their hands on an owner's manual and it shows that version of the engine requires 91-octane fuel to run. Knowing that, it probably won't be any cheaper to drive than a fuel-slurping V8, but I don't think that was ever the point.
It's worth noting straight away that only the high-output inline-six requires premium gas. The 3.6-liter Pentastar V6 and the standard-output Hurricane 3.0-liter both run just fine on 87 or 89 octane. Really, it shouldn't come as a surprise that the H.O. needs better fuel. It makes an extra 120 hp and 52 lb-ft of torque compared to the regular Hurricane with the same displacement.
Although the EPA hasn't posted fuel economy figures for the new Ram 1500 just yet, we can estimate the mileage difference based on the Jeep Wagoneer and Grand Wagoneer. Those SUVs recently made the switch from a V8 to the Hurricane inline-six and saw improvements of 1 or 2 mpg. Moving to a smaller engine with forced induction was never about massive gains in fuel efficiency; it's about performance and emissions. We saw Toyota do the same with its large body-on-frame vehicles, even going a step further by adding a hybrid system to some Tundras and all Sequoias.
It was almost a shock when Stellantis announced its new internal combustion engine back in 2022 amidst the industry-wide push for electrification. We talked with the manufacturer and published a story breaking down exactly how the Hurricane inline-six makes more power more efficiently with less displacement: high-pressure fuel delivery, low-inertia turbochargers, water-to-air charge cooling, and fancy new cylinder bore coating to lessen mechanical friction. A Stellantis spokesperson is also quoted in that article saying, "The Hurricane I6 is designed and optimized from the ground up for its targets of reduced emissions and improved power." You'll notice that "cheaper ownership" isn't mentioned anywhere in there.
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