The inline six has long been considered one of the most balanced and naturally smooth engine configurations ever built. It delivers effortless torque, refined power, and reliability that often outlives the cars it powers. From classic British sports cars to Japanese performance icons and rugged American workhorses, the inline six has shaped automotive history in ways that no other engine layout can claim. Some earned their reputations on racetracks, others on farms or construction sites, but all of them set a standard that remains respected to this day.
Jaguar XK Straight Six
The Jaguar XK engine made its debut in 1949 and stayed in production for nearly four decades, a testament to its brilliance. It came in a variety of displacements ranging from 2.4 to 4.2 liters and was as smooth as it was powerful. This engine powered everything from the XK120 sports car, which stunned the world with its speed and elegance, to the legendary E Type that became the face of British motoring in the 1960s. It also proved itself in endurance racing, taking victories at Le Mans and other iconic circuits. Today, cars fitted with the XK straight six command serious value in North America, with E Types often selling for over one hundred thousand dollars. Collectors know that the heart of those cars was an engine that combined race winning performance with the sophistication expected of a Jaguar.
BMW M30
BMW’s reputation for silky smooth straight sixes was built on the M30, which ran from the late 1960s well into the 1990s. Known as “the big six,” it powered models like the 5 Series, 6 Series, and 7 Series. It was not only powerful but incredibly durable, with many examples still running strong today after hundreds of thousands of miles. The M30 made BMW the go to choice for buyers who wanted both performance and refinement in a luxury sedan. In the United States and Canada, early BMWs with this engine have become increasingly collectible, especially the E24 6 Series coupes and E28 535i sedans. The M30 demonstrated that luxury cars could be engaging to drive without sacrificing reliability, setting a standard that BMW would build on for decades.
Mercedes Benz M110
The M110 engine arrived in the early 1970s with twin overhead camshafts and an emphasis on smooth power delivery. It served faithfully in the W123 sedans and coupes, as well as early versions of the S Class. While it was never designed to be a performance monster, its reputation for refinement and longevity helped Mercedes cement its image as the world’s premier luxury brand. These engines were engineered to last, and many are still running in Canada and the U.S., often with odometers well past three hundred thousand miles. The M110 may not command huge collector premiums, but it remains a symbol of engineering that put reliability and refinement first, something many modern cars fail to match.
Toyota 2JZ GTE
When Toyota unveiled the 2JZ GTE in the early 1990s, it set a new global standard for durability and tuning potential. Fitted to the Mk4 Supra, the twin turbocharged straight six produced over 300 horsepower stock but was famous for handling four figure horsepower numbers with little more than upgraded turbos and fueling. Its iron block, robust internals, and smooth delivery made it beloved by tuners across North America. The 2JZ became the darling of drag racers, drift enthusiasts, and street tuners, cementing its status as the king of Japanese engines. Today, Supras equipped with the 2JZ sell for astronomical prices, often well into six figures in both the U.S. and Canada. Even standalone 2JZ engines can fetch tens of thousands, proving that its legend is alive and well.
Nissan RB26DETT
The RB26DETT was Nissan’s answer to Toyota’s 2JZ, powering the Skyline GT R through the late 80s and 1990s. With twin turbos, an iron block, and a rev happy nature, it became the heart of a car nicknamed “Godzilla” for its dominance in motorsport. The RB26 was designed with racing in mind, and its success in Group A touring car championships proved its capability. For years, these engines were forbidden fruit in North America due to import restrictions, which only made their mystique stronger. Now that Skylines are legal to import, values have skyrocketed, with clean GT Rs selling for over one hundred thousand dollars and RB26 engines themselves prized by builders. It set the bar for what a Japanese performance straight six could achieve.
Chrysler Slant Six
Chrysler’s Slant Six, introduced in 1960, wasn’t about outright performance—it was about indestructibility. With its cylinders tilted at thirty degrees to fit under low hood lines, it became a workhorse engine for Dodge and Plymouth cars and trucks. Farmers, taxi drivers, and fleet operators swore by it because it would run forever, even with minimal maintenance. It was underpowered compared to V8s, but its torque and reliability made it beloved. In the United States, Slant Six powered cars and trucks are still running on farms and job sites, proof of its toughness. Collectors don’t pay huge premiums for Slant Six cars, but among enthusiasts it enjoys a cult following as one of the hardest engines to kill.
AMC 4.0 Inline Six
The AMC 4.0, which lived on in Jeep models until 2006, was another legend of longevity. Introduced in the late 1980s, it quickly became the backbone of the Cherokee, Wrangler, and Grand Cherokee. Its cast iron block and torquey character made it perfect for off road use, and countless examples are still running today with over 300,000 miles. Jeep enthusiasts across North America call it the best engine the company ever made. Collector interest has grown as vintage Cherokees and Wranglers have become hot property, with many buyers specifically seeking models equipped with the 4.0. It was simple, reliable, and strong, proving that not all legends are built in racetracks—some are built on trails.
Ford 300 Inline Six
Ford’s 300 cubic inch straight six was a staple of American pickups from the 1960s through the mid 1990s. It was designed for torque, durability, and simplicity. Farmers and contractors loved it because it would run under any condition and pull heavy loads all day without complaint. It wasn’t glamorous, but it became a legend in its own right. Many Ford owners in the U.S. and Canada still brag about trucks with 300 sixes that have racked up half a million miles. Collectors prize them not for high values but for their working class credibility. It represents an era when engines were designed to be unbreakable tools rather than disposable technology.
BMW S54
The BMW S54, launched in the early 2000s but directly connected to the brand’s inline six heritage, is often considered one of the finest naturally aspirated straight sixes ever built. Found in the E46 M3, the Z3M, and the Z4M, it produced over 330 horsepower from just 3.2 liters. It used individual throttle bodies, high compression, and a high redline to deliver an engine that combined smoothness with motorsport DNA. The S54 is still revered today in North America, with E46 M3s climbing in value as enthusiasts recognize the brilliance of this powerplant. Clean, low mileage M3s often fetch forty to sixty thousand dollars and rising, proving how desirable this engine has become. It set the standard for modern performance sixes.
Aston Martin DB4 Straight Six
Aston Martin’s straight six designed by Tadek Marek for the DB4 in the late 1950s deserves recognition as one of the most influential. It combined power, smoothness, and prestige in a way that elevated Aston Martin into the global spotlight. This engine went on to power the DB5, forever immortalized as James Bond’s car. In North America, DB4s and DB5s sell for millions at auction, much of their value tied directly to the refinement and performance of this engine. It showed that the inline six wasn’t just for workhorses or family cars—it could power some of the most glamorous grand tourers in history.
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25 Facts About Car Loans That Most Drivers Don’t Realize
