With environmental concerns being arguably the largest factor driving modern engine development, it shouldn’t come as a surprise that most powerplants are getting smaller and more efficient by the year. Larger and naturally aspirated engines are becoming few and far between, with more compact four and six-cylinder engines equipped with turbochargers and hybrid systems becoming ever more prevalent throughout the automotive kingdom. This is the most powerful inline-six configuration currently on sale in 2026, with the winner claiming the crown purely due to its potent electric setup.
Base Trim Engine
3L AMG I6 Hybrid
Base Trim Transmission
9-speed automatic
Base Trim Drivetrain
All-Wheel Drive
Base Trim Horsepower
443 HP @5800 RPM
Base Trim Torque
413 lb.-ft. @ 2200 RPM
Base Trim Battery Type
Lead acid battery
Infotainment & Features
9 /10
This piece explores the most powerful inline-six powertrain on sale in 2026, including the engine and any kind of off-board powertrain, such as a hybrid system. All data used was sourced from reputable providers.
Mercedes-Benz’s M256 Hybrid Engine Is The Most Powerful Of Its Breed In 2026
Red 2024 Mercedes-AMG GT 43 I6 engineMercedes-AMG
The winner of this particular contest is Mercedes-Benz’s M256 straight-six engine, which first debuted in 2017. It was the brand’s first inline-six engine since the M104 exited production in 1999, with the unit replacing the dependable M276 V6 engine. Initially, it was only available in the S 500 model, though a year after its inception it made its bow in most of Mercedes’ sedan range, such as the C-Class and E-Class, before it reached the AMG-GT sports car and GLE SUVs in 2019.
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The unit is turbocharged, and comes predominantly with a 3.0-liter displacement. There is also a 2.5-liter version of the M256, though this one is reserved for the Chinese market in special versions of the GLE and S-Class. In most models it features in, it also makes do without the assistance of any kind of full-time hybrid system. As a result, the solo engine in its most powerful form only produces 429 hp, making it less powerful than similar engines produced by BMW and Stellantis.
Mercedes Has Recently Developed A More Powerful Version For Its E-Class
2026 Mercedes-AMG E53 Wagon 3.0L Turbo I6 M256 Hybrid EngineMercedes-Benz
Feeling it had more potential though, Mercedes elected to equip it with a potent single-electric-motor hybrid system to boost power exponentially for use in its 2026 E 53 AMG sedan, which first hit the road in 2024. The EV powertrain alone brings 161 hp to the party, which, when combined with the most powerful version of the M256, means the E 53’s total system output is a commanding 604 hp. The combined powertrain is currently only available in the E 53 Hybrid sedan, though Mercedes recently announced that a wagon version of the model will also use the powerplant.
Discussion
What is your favorite engine configuration?
Volkswagen recently built its final VR6 engine, which got us thinking about all the engine configurations out there. These days, the most prominent engine options are inline fours and sixes, but there are several to choose from.
You have the beloved V8, which powers sports sedans to pickup trucks and everything in between, and the sonorous V12, which is traditionally a supercar engine. The V6 is more of a workhorse, while the V10 is rare and also associated with exotica. We can’t forget Audi’s beloved turbocharged inline-five, or VW’s groundbreaking W12. Bugatti used to build W16 engines, but the Tourbillon will use the first V16 engine in more than 80 years. And let us not forget about classic motors like the straight eight, or engines associated with one particular brand. Like Subaru and the flat-four, or Porsche’s turbocharged and naturally aspirated flat sixes. Which engine configuration is your favorite, and why?
It doesn’t use its full 604 hp all the time, with the full amount of power being accessible when using the vehicle’s Race Start launch control system. Normally, the powertrain runs with 577 hp. Either way, this makes it the most powerful inline-six powertrain available in 2025.
The E 53’s Powertrain Is A Technological Marvel
Mercedes-AMG E53 WagonMercedes-Benz
One thing is for sure, Mercedes’ engineers weren’t messing about when developing the M256. The decision to move back to an inline-six layout from the previous V6 was made mainly due to weight and simplicity, as the more naturally balanced inline configuration ensures that fewer parts are needed to get the engine firing on all cylinders. Not only does this reduce overall weight, it also reduces friction, preventing the engine from having to work as hard. This means less power is lost in the combustion process and less heat is produced, helping enhance reliability.
2024-Present Mercedes-Benz M256 Hybrid Specifications
Block and Head Material
Aluminum
Valve gear
DOHC w/ 4 valves per cylinder
Bore/Stroke
3.26 x 3.63 inches
Aspiration
Turbocharged
Power
577 hp (604 hp with Race Start)
Torque
553 lb-ft
Models Featured
E 53 sedan, E 53 wagon
Mercedes was also able to find the space needed to place the vehicle’s catalytic converters closer to the engine’s turbocharger, which allows it to reach a better operating temperature. This means it can work more effectively in reducing the emissions coming out of its exhaust, ensuring it’s even better for the environment. The engine’s block and cylinder heads are made from lightweight aluminum to help keep weight to a minimum.
The Hybrid M256 Uses A Genius Turbo/Supercharger Partnership To Reduce Lag
Mercedes-AMG E53 on the roadMercedes-Benz
One of the most interesting and advanced elements of the M256 is the use of a small supercharger, which works to help produce power and start the engine. This means a traditional starter motor isn’t needed, but the electric supercharger comes with the benefit of offering extra boost to the engine. Superchargers don’t feature any kind of lag as they run directly off the engine, unlike a turbocharger that runs off wasted exhaust gases. As the gases only turn up when the engine has finished its combustion process, there is a delay before it can start working.
The supercharger, which produces 20 hp and 162 lb-ft of torque on its own, works at lower revs to fill in the torque gap left by the turbo, ensuring lag is completely eradicated. The use of the supercharger also ensures that a larger single turbo can be used, rather than utilizing two smaller turbos, which add extra weight to the setup. When twinned with the hybrid system and rapid-fire nine-speed automatic gearbox, the 577-hp M256 means the E 53 can blast from 0-60 mph in 3.9 seconds. Not bad for a family sedan.
You’ll Need Deep Pockets To Get A Full-Hybrid M256 In Your Life
2025 Mercedes AMG E53 Hybrid rear three-quarters angle in white while parkedMercedes-AMG
You’ll need to hand over $89,600 to grace your life with one, though you do get most of the options thrown in for the price, with most remaining extras tending to focus on styling tweaks that many drivers will likely not worry too much about, such as the $1,750 AMG Carbon exterior package.
2025 Mercedes-AMG E53 Sedan PHEV Interior DashboardMercedes-AMG
You’ll also be treated to a range of interior refinements, such as heated and ventilated front seats, dual-zone climate control, and a natural light-boosting panoramic sunroof. These will come in handy when trying to lower your heart rate after making the most of that beastly inline-six sitting proudly out front.
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Stellantis’ Mighty Hurricane Engine Runs The M256 Close In Terms Of Power
2025 Ram 1500 Hurricane 3.0L Twin-turbo I6 EngineRam
While the Mercedes-Benz M256 is currently the most powerful inline-six powerplant on the block, Stellantis’ High Output 3.0-liter Hurricane engine used in the 2025 RAM 1500 Tungsten, and upcoming Dodge Charger SixPack, runs it close. Unlike the M256, the Hurricane HO doesn’t utilize any kind of hybrid system, and uses a pair of high-flow turbos as opposed to the single component used on Mercedes’ contender. Despite the lack of any kind of electrical assistance, the Hurricane HO produces a commanding 540 hp and 521 lb-ft of torque.
2024-Present Stellantis Hurricane HO Specifications
Block and Head Material
Aluminum
Valvegear
DOHC w/ 4 valves per cylinder
Bore/Stroke
3.31 x 3.54 inches
Aspiration
Twin-turbocharged
Power
540 hp
Torque
521 lb-ft
Models Featured
RAM 1500, Dodge Charger SixPack H.O
It needed to be powerful, as it replaces the legendary Hemi V8 in Stellantis’ engine lineup. The powerplant was built tough, too, which is lucky given the amount of grunt it produces. While it utilizes aluminum to keep weight down, forged connecting rods and crankshafts are used to ensure the engine remains rock solid long-term, while cross-bolted steel bearing caps are used to keep the rotating assembly firmly fixed in place.
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And that’s not the only thing it’s slower than.
It may not be quite as powerful as Mercedes’ combined powertrain, but the Hurricane HO performs admirably, given that it relies purely on its ICE to make the grunt, rather than have a potent EV powertrain to rely on like the M256 does. There’s nothing like a bit of American muscle.
Sources: Mercedes-Benz, Stellantis.
