The Most Powerful Inline 6 Engines Ever Made

There’s the classic V8, and then the darling of the 1960 and 1970s, the silky smooth V12. But one configuration stands out as a sweet spot for manufacturers, and also as a performance monster – the inline-six. Yes, even with a dip in popularity in the modern era of turbocharged inline-fours, straight-six engines stay the course as a deliverer of power and smoothness.

Will the straight-six ever fade completely? Maybe. Smaller, turbocharged engines provide both lower emissions, good power and low consumption, making them ideal for family cars. But at the moment, there are still a handful of automakers who still believe in the magic of the straight six.

10 Nissan Skyline GT-R

276 HP

No list would be complete with one of the icons of Japanese car culture in it, the Skyline GT-R. In 1989, Nissan resurrected its stunning sports car, the Skyline GT-R, gracing the new R32 model with grippy all-wheel drive and a powerful twin-turbo 2.6 liter straight-six engine. The engine’s designation — RB26DETT — was in classic Japanese style, a mouthful in itself, but was short for Response Balance Double Overhead Cam Electronic Twin Turbo.

Highly tunable

This was still the early days of turbocharging in production cars, thus the power figures are not as big as what we see today, even if the cars used twin-turbochargers. The stock version produced 276 hp, but as it was an unstressed engine (an internal agreement between Japanese carmakers to limit safety concerns) it was very tunable. Removing the restrictor and toggling the computer, and diligent tuners got the 2.6-liter up to 1,000 hp.

9 Toyota Supra

320 HP

Here is another Japanese engine with an insane name: the 2JZ-GTE. In the same 1990s era that the likes of Mitsubishi and Nissan started experimenting with twin-turbo engines, Toyota came up with its own 3.0-liter-inline-six for its midsize sports cars. The engine debuted on the Lexus GS300 in Japan in 1989, but first came to America in the 1993 Supra.

The naturally aspirated version had only 230 ponies, but the turbocharged version muscled out 320 horsepower. The 2JZ-GTE was rock-solid thanks to a cast iron block, a forged steel crankshaft, and oil injection points underneath the pistons, making it very popular with enthusiasts for upgrades, easily reaching up to 700 hp.

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8 Aston Martin DB7

335 HP

Hopping over to the Old Continent, the British carmaker Aston Martin had a love affair with the straight six of its own. When its rival, Jaguar, came up with a supercharged 4.0-liter-V8 producing 320 hp for its XJR, Aston Martin returned in 1993 with a blown straight-six that pumped out 335 hp. But, to rub more salt into the wounds, their engine size was only 3.2-liters.

On the technical front, the cylinder head used 4 valves per cylinder with Zytec electronic multipoint fuel injection while the air needed to combust the fuel was delivered by water-cooled supercharger. All which meant that the DB7 churned out more power from a smaller engine than the Jag, James.

7 Mercedes-Benz S-Class Diesel

335 HP

We love a curveball, and this time it is courtesy of the team from Stuttgart. Mercedes loves their straight sixes, as we’ll see down below again. But Heinz, Fritz and Günther has not just kept it to petrol engines alone. In the S-Class, there is a very cool inline-six to be enjoyed for its smooth, powerful drive that it provides, accompanied by the big torque qualities of diesel engines and low fuel consumption.

The OM656 D29T SCR is a beast with a difficult name and a powerful punch. The base version of the engine delivers 286 hp from its 2.9-liters displacement, using two turbochargers. However, the more powerful version hits a mighty 335 horses, making it one of the most powerful diesel engines out there. The German automaker currently employs it in its flagship S-Class luxury sedans, though it’s not available in America.

Of course, it has to be remembered that diesel engines by nature don’t lean themselves to high rpm’s, which automatically constricts their horsepower figure. But thanks to modern tubo-technology, they can still crank up a good speed, and thus give us these higher than usual horsepower figures.

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6 Volvo S60 T6 R

345 HP

Safe and secure, right? Those Swedes from Volvo are renowned for their big, boxy family sedans and wagons. But since the early 2000s, the Swedish automaker has sought to pump a bit of red blood into those icy veins, producing a handful of interesting performance models. One of which was the second edition of its executive sedan, the S60. With the help from tuning specialist Polestar, the 2013 model year S60 T6 R got its 2.5-liter-inline 5 with turbocharger upgraded to a 3.0-liter-straight six. Power shot up to 335 hp, and thanks to all-wheel traction, Swedish drivers could dodge pesky elks with ease without tapping off.

5 Land Rover Defender

395 HP

Think of Land Rover and big, boxy SUVs come to mind, ready for crossing the savanna. But underneath the hood of modern Landies there are some gems to be found. Like their new 3.0-liter straight-six in the Defender, which produces 395 horsepower and 406 pound-feet of torque. It’s tagged the P400, and features a mild hybrid motor that helps the electric supercharger get up to speed quickly without using engine power.

Adding an intercooler into the mix, it is no surprise the hefty Defender weighing over 5,000 pounds can accelerate to 60 mph in just 5.7 seconds. If you want even more power, the Defender Octa is what you want.

4 TVR Speed Six

400 HP

As one of the niche British sports carmakers, TVR has always been on the fringe of the motoring fraternity. For years, the group used Rover V8 engines, tuned to their own specifications, to power their hand built sports cars. But with the selling of Rover to BMW in the late 1990s, the automaker had to make a new plan.

The answer was an independently designed new inline-six, with a 3.0-liter displacement. One of the first models to use the Speed Six engine was the 2004 Sagaris. A beast of a sports car, but with a reputation for being unreliable as well. But with 400 horses on tap, owners were just happy enough to enjoy that power available under foot.

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3 Mercedes-Benz S-Class

429 HP

Reaching the top-three of our list, it is not uncommon to see the name of a Mercedes product again. Stuttgart has always been famous for its big inline-sixes, and a good, modern example is the 3.0-liter petrol version currently being used in the S-Class. Codenamed the M256, the turbocharged engine debuted in America in the 2019 CLS and E53 AMG versions. In a clever system, the M256 uses a 48V electrical system to operate an electrical supercharger to reduce turbo lag.

The response is thus smooth and quick, helping the big S-Class to accelerate efficiently even for a big sedan.

2 Jeep Wagoneer HO

510 HP

One of the newest kids on the block is the Stellantis Group’s 3.0-liter-inline-6 with twin turbochargers. Codenamed the Hurricane, the engine is to be used in all of its performance models, and one of the first to receive it was the new Jeep Wagoneer. The all-new Dodge Charger Six-Pack models are not on this list yet because they haven’t gone on sale, but you can look forward to 550 hp.

The company says the new engine delivers more horsepower, more torque and fewer emissions than many competitors’ naturally aspirated V8 and boosted six-cylinder engines. In the Wagoneer’s case, power is an impressive 510 hp and 510 lb-ft of torque.

1 BMW M4 CSL

543 HP

Throughout the years, BMW has created a lot of special inline-sixes, mostly used in recent years in its 3-Series sedans and smaller performance cars. The latest version of their family of Big Sixes is the S58. It debuted in the 2020 X3M, producing a whopping 503 hp. But recently a more powerful version was launched with a staggering 543 hp, boiling under the hood of the very special M4 CSL.

That’s enough horses to shoot it up right to the top of our list of most powerful straight-six engines in production cars. And leave us to drool over the glory days of the combustion engine for a while longer.

Sources:
BMW
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Mercedes-Benz
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Toyota
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Nissan
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Stellantis