The inline-six engine has a long history in automotive engineering because of its inherent mechanical balance and smooth operation. It has good inherent balancing of primary and secondary forces and, as a result, doesn’t need additional balance shafts to sustain steady torque production. The number of automakers that have adopted this engine architecture for their own use, now that most manufacturers shifted to compact V6 engines as a packaging solution, is limited, but this engine type does have some fans among those building performance vehicles, luxury automobiles, trucks, and SUVs.

Modern computer-aided design, high-tech aluminium casting and sophisticated forced induction have breathed new life into this old-school design. In 2026, seven manufacturers are still choosing to develop inline-six engines with advanced design and engineering, for more power, more efficiency and more longevity. BMW and Mercedes-Benz, long advocates of the six-cylinder concept, are well represented but Stellantis, Mazda, General Motors, Jaguar Land Rover and Cummins have also made use of the configuration in various segments, showing that the traditional six-cylinder package can still be competitive in both performance and refinement, as well as having the required output.

1. BMW

BMW is the engine of choice for BMW fans The inline-six has been strongly associated with BMW, even though various rivals long ago swapped out a relatively large V-6 for a shorter, more nimble alternative. Over the years, BMW has kept the inline-six as a core powertrain in its sporty sedans and coupes, and the brand new turbocharged 3.0-liter B58 engine and motorsport-derived S58 sibling are the latest versions of the core drivetrain. Both engines provide impressive yet refined power BMW has continued to evolve the inline-six engine, and a winner for sure.

BMW Inline-Six Engine Highlights:

• Turbocharged 3.0-liter B58 engine
• Motorsport-inspired S58 engine
• Up to 543 horsepower
• Closed-deck aluminum block
• Forged steel crankshaft

Vehicles with the B58 engine, which includes the M340i and Z4, now delivers 382 hp and 369 lb-ft of torque. The high-performance S58 twin-turbo engine in the M4 CSL goes even further, outputting as much as 543 hp. These engines feature a closed-deck aluminum block, forged steel crankshaft, and wire-arc thermal-sprayed cylinder coatings to accommodate increased boost pressure precision CNC machining and tight manufacturing tolerances promote structural integrity and thermal efficiency. On the road, these engines are known for instant throttle response and silky mechanical sounds, with a balanced firing order minimizing unwanted vibration for daily refinement and high-performance durability.

2. Mercedes-Benz

Mercedes-Benz, after all, has been living a V-6 horsepower and torque diet for far too long. Their engineers appreciated the inherent, smooth, easy-to-modulate geometry of the inline-6 and managed to incorporate it into their modern M256 family of three-liter engines, which utilize 48-volt electrical hybridization. This new architecture blends classic six-cylinder design with a hybrid electric boost and a smattering of mild hybrid assist, all while working to provide a motoring experience that is engine-efficient and free of destructive parasitic losses. Mercedes uses a variation of this new-but-old architecture in its high-end luxury and performance models, with a straight-six that employs hybridization as a natural enhancement to this venerable six-cylinder layout.

Mercedes-Benz M256 Engine Features:

• Modern 3.0-liter inline-six
• 48-volt electrical hybridization
• Up to 429 horsepower
• Integrated starter-generator assistance
• Electric auxiliary compressor

In normal luxury trim, the M256 makes 362 horsepower, while more performance-oriented AMG versions make 429. The integrated starter-generator further adds 21 horsepower of electric juice. Mercedes also removes accessory belts, which can spin parts such as the water-pump and air-conditioning compressor through the 48-volt circuit. An electric auxiliary compressor help fills in power fevers before the combustion-powered turbo begins to hit maximum pressure. Tighter yet, Mercedes uses aluminum die casting and automated inspections, dual-overhead camshafts, and CAMTRONIC variable valve timing for reduced emissions and efficient operation. It all combines for effortless, cloud-free accelerative haste with all the assist modern hybrid powertrains bring.

3. Stellantis

A new generation of turbocharged engines has set a benchmark. (photo above) Stellantis’ clean-sheet 3.0-liter Hurricane twin-turbo engine was developed specifically to lead a gradual transition of popular vehicle lines away from tried-and-true naturally aspirated Hemi V-8s. The company engineered this all-new powerplant to be a true upgrade that would power demanding applications such as trucks and SUVs while surpassing the proven performance of naturally aspirated engines. Now available through Jeep, Dodge and Ram brands, the Hurricane’s twin-turbo setup, in tandem with targeted fuel injections, will combine the power and capability of large-displacement engines with better fuel efficiency.

Stellantis Hurricane Engine Specifications:

• Clean-sheet 3.0-liter engine
• Twin-turbocharged inline-six configuration
• Standard Output 420 horsepower
• High Output 510 horsepower
• Direct injection up to 5,075 psi

The Hurricane is offered in two configurations Standard Output (SO) with 420 hp and 468 lb-ft of torque, and High Output (HO), with 510 hp and 500 lb-ft of torque. Both forms of the engine use twin low-inertia turbochargers, along with high-pressure direct injection at 5,075 psi, and employ a deep-skirt cast-aluminum engine block with cross-bolted steel main bearing caps. Stellantis has also applied plasma transfer wire arc (PTWA) coating to the bore cylinders along with automated precision assembly, to maximize durability during frequent, real-world use while towing heavy loads. Its torquey, linear power and refinement make it an important element of the new inline-six revival.

4. Mazda

Mazda surprised the automotive industry by developing a new rear-wheel-drive platform built around a fresh straight-six engine family. The 3.3-liter e-Skyactiv G turbocharged inline-six serves as a central component of this architecture, powering premium crossovers such as the CX-70 and CX-90. Rather than limiting the engine to traditional sports cars, Mazda introduced it into the premium family vehicle segment. In its top-tier specification, the powerplant produces 340 horsepower and 369 lb-ft of torque. Its combination of turbocharged performance and smooth inline-six operation is intended to provide a refined grand-touring character for larger vehicles.

Mazda 3.3-Liter Inline-Six Features:

• 3.3-liter turbocharged engine
• e-Skyactiv G technology
• Up to 340 horsepower
• 369 lb-ft of torque
• 48-volt M-Hybrid Boost system

Separately, Mazda includes a 48V M-Hybrid Boost system that’s installed between the engine and transmission to enable hybrid-assisted operation. Its engine features an advanced combustion system named DCPCI to maximize thermal efficiency, along with precise aluminum block casting and automated engine assembly to minimize reciprocating mass to keep the engine feeling sharp and eager to rev. Mazda’s work on the powertrain means that the inline-six powers the car without feeling the least bit dull, able to produce loads of torque through a twisty road with a distinctive exhaust note. Development of the engine also proves that the six is just as right at home in a premium family crossover as it is in a performer.

5. General Motors

GM’s approach to the modern straight-six revival has been quite different, as well. The brand’s turbocharged straight-six is available on full-size trucks and SUVs, with a 3.0-liter Duramax turbo-diesel engine known as the LZ0 in its second-generation form. Diesel engines are tuned not to simply show their best on the dyno, but to propel a vehicle with excellent torque, and GM’s diesel straight-six does just that, offering impressive 305 horsepower and 495 lb-ft. Of torque, available at low engine speeds. The result is a smooth, powerful powertrain with impressive pull.

GM 3.0-Liter Duramax Highlights:

• Second-generation LZ0 engine
• 305 horsepower output
• 495 lb-ft of torque
• Cast-aluminum engine block
• Forged steel internal components

Instead of the weighter, cast-iron block, GM employs a cast-aluminum block with spun-cast iron cylinder sleeves. That helps shave weight from over the front axle and, with a pair of forged steel connecting rods and a forged crankshaft, handle the cylinder pressures brought on by a high-pressure common-rail fuel injection system. Dedicated engine machining and balancing sets the engine apart with a smooth, quiet finish for quiet highway cruising and as much fuel range as the largest of SUVs, but enough grunt, refinement and truck capability to make the inline 6 an essential, high-volume engine in GM larger vehicles.

6. Jaguar Land Rover

Jaguar Land Rover. JLR engineered a sophisticated inline-six with a capacity of 3.0 liters to push a handful of the most prominent products in the lineup (range rover, Defender, F-Pace and so on). The P400 version offers 395 horsepower and 406 lb-ft torque (according to Jaguar Land Rover). Jaguar Land Rover couples the classic inline six with forced induction and electrical pulsing to improve throttle response and optimize the execution of the engine. The six-cylinder has been available in various prestige SUVs and performance use cases, which shows its versatility.

JLR Ingenium Engine Features:

• Modular Ingenium powertrain family
• 3.0-liter inline-six engine
• Up to 395 horsepower
• 406 lb-ft of torque
• 48-volt electric supercharger assistance

A combination of a twin-scroll turbocharger and 48V electric supercharger minimizes lag off-idle. Its machining process features precision CNC milling, robot inspection, and close machining tolerances. Continual variable valve lift and direct cylinder injection optimize combustion across a range of loads and speeds. All these technologies serve to create a powerplant capable of unleashing an even, linear rush of acceleration for nearly any driving scenario. Be it tackling rocky off-road trails, or cruising at top speeds on the motorway, JLR has engineered an inline-six engine that not only plays well in the realm of luxury but can handle the rigorous demands of the rugged countryside.

7. Cummins

Caterpillar family, Cummins has always been one of the big names in the straight six game especially for heavy-duty diesel trucks and industrial applications. Its turbo diesel 6.7L inline-six diesel that powers the heavy-duty Ram 2500 and 3500 is a proven workhorse. Built specifically with challenging towing applications and commercial trucking-style use in mind, it leans heavily into low-end torque and endurance, and it boasts an output of 420 horsepower and 1,075 pounds-feet of torque in high-output form. Those are the kind of specs that play in the mountains pulling heavy loads up steep grades.

Cummins 6.7-Liter Diesel Features:

• 6.7-liter Turbo Diesel engine
• 420 horsepower in high-output trim
• 1,075 lb-ft of torque
• Compacted graphite iron block
• Forged steel pistons

Strong block Iron block of compacted graphite offers exceptional strength, stiffness and vibration absorption in the engine without the weight of traditional cast-iron. Forged pistons and balanced components within the engine make the unit capable of handling the stresses of heavy-duty operation. Heavy-duty engine testing also signifies the durability of the Cummins powerplant, ideal for heavy-duty cycles and elevated boost levels. With decades of heavy-equipment experience to draw upon, the Cummins diesel engine is known for its durability, towing power and workhorse performance. The 6.7-liter diesel engine in Ram heavy-duty trucks provides the low-speed pulling power for extreme work.