The Bentley Mulsanne looks like a stately old-world limousine, but beneath its long bonnet sits one of the most outrageous powerplants ever fitted to a production sedan. Its vast twin-turbocharged V8 is not only a technical curiosity, it is also a rolling farewell to a very specific kind of excess that is rapidly disappearing from the luxury market.
By hiding the largest twin-turbo V8 in a car that prioritizes leather, wood and silence over spoilers and wings, the Mulsanne turns the idea of a “sleeper” on its head and reframes what a flagship limousine can be. I see it as the last, loud heartbeat of a tradition that stretches back decades, even if the car itself whispers rather than shouts about its performance potential.
The sleeper sedan with a giant secret
From the outside, the Bentley Mulsanne projects formality rather than fury, with a three-box silhouette and upright grille that could pass for a classic chauffeur car. That is exactly why its mechanical specification is so startling: buried under the hood is what has been described as the world’s biggest twin-turbocharged V8 fitted to a sedan, a configuration that turns this dignified four-door into a genuine sleeper. Reporting on the car highlights that The Bentley Mulsanne Features a 6.75-Liter twin-turbo unit, a figure that dwarfs the engines in most modern performance saloons.
The contrast between appearance and capability is central to the Mulsanne’s appeal. In coverage dated Nov 23, 2025, the same analysis of this “sleeper” emphasizes that the Bentley Mulsanne combines a huge and stately body with that 6.75-Liter V8, making it a three-ton luxury sedan that can move with startling urgency when provoked. The piece notes that Nov and Liter Twin Turbo are not just marketing phrases but shorthand for an old-school engineering philosophy that prioritizes effortless torque over high-rev theatrics, and it is this philosophy that lets the Bentley Mulsanne hide its true character in plain sight.
Inside the 6.75-Liter twin-turbo V8
At the core of the story is displacement, and the number itself is non-negotiable. The Mulsanne’s engine is repeatedly identified as a 6.75-Liter twin-turbo V8, a capacity that would be remarkable in any context and is almost unheard of in a modern production sedan. Technical breakdowns of the car underline that this 6.75-Liter layout is paired with twin turbochargers to deliver immense low-end torque, allowing the Bentley Mulsanne to surge forward with minimal effort and very little drama from behind the wheel. One detailed drive report even points out that the real star of the car is this powerplant, describing how the thrust the engine provides is almost unbelievable for a three-ton vehicle, a claim anchored in testing that highlights how the 6.75-Liter twin-turbo setup transforms the driving experience.
What makes this V8 particularly interesting is how it balances heritage and modernity. The displacement figure is rooted in a long Bentley tradition, yet the addition of twin turbochargers and contemporary electronics means the engine can deliver towering performance while still meeting the refinement expectations of a flagship limousine. A closer look at the powertrain notes that the Bentley Mulsanne’s unit is tuned for a wave of torque rather than headline-grabbing peak power, and that the way the Liter Twin Turbo combination responds at low revs is central to the car’s character. Another focused technical discussion of the same engine stresses that the Bentley Mulsanne uses its Turbo hardware not for theatrical turbo lag or high-rpm fireworks, but to ensure that the 6.75-Liter V8 always has more shove in reserve than the driver is likely to need, a point underscored in coverage that calls the engine’s thrust almost unbelievable.
A lineage built around 6¾ litres
The Mulsanne’s engine is not an isolated engineering stunt, it is the culmination of a lineage that Bentley has been refining for decades. Official material on the model explains that the car is inspired by, and takes its name from, the legendary 6¾-litre engine, which reached its 60th anniversary in the same period that the final Mulsanne was being celebrated. That heritage piece notes that designers even created special artwork and drawings of the engine itself to mark the milestone, underlining how central this displacement is to the brand’s identity. The same source describes how Bentley Motors, which employs around 4,000 people at Crewe, used the Mulsanne to showcase the history and evolution of this 6¾-litre V8, a point captured in the official account of how the car is inspired by that engine.
Looking back to the start of the modern Mulsanne’s life, contemporary reporting from Apr 7, 2010, makes clear that this was never meant to be just another big luxury sedan. One early profile notes that While the V8 configuration and 6¾-litre displacement were already familiar and favoured at Crewe, the Mulsanne enjoyed the very latest iteration of that formula, with extensive reengineering to meet modern expectations. That same piece highlights how the Mulsanne could still deliver a swift 5.3 seconds to typical benchmark speeds despite its size, illustrating how the Crewe engineers used the long-running 6¾-litre architecture as a foundation for contemporary performance. By tying the car so explicitly to this displacement, Bentley signalled that the Mulsanne was intended as the beating heart of its traditional engineering culture rather than a clean-sheet break from the past, a theme that runs through the beating heart coverage.
How the Mulsanne’s specs stack up
On paper, the Bentley Mulsanne’s numbers are as striking as its physical presence. Technical summaries of the model list the Bentley Mulsanne Engine as a 6.75 L twin-turbocharged V8, a specification that immediately sets it apart from the smaller, higher-revving units that dominate the modern performance sedan segment. That 6.75 figure is not just a rounding of the 6¾-litre heritage badge, it is the formal metric used in contemporary documentation, and it underscores how far Bentley was willing to go in pursuit of effortless power. When you combine that displacement with the car’s substantial curb weight and limousine packaging, you end up with a specification sheet that reads more like a grand touring coupe than a traditional four-door, a point that is clear in the Bentley Mulsanne Engine overview.
Context matters when assessing whether this is truly the largest twin-turbo V8 in a sedan, and the available reporting leans heavily in that direction. The same sources that emphasize the 6.75 L figure also note that rival luxury sedans have largely shifted to smaller displacement V8s or even V6 hybrids, making the Mulsanne’s configuration an outlier. When I compare the Bentley Mulsanne’s engine to those competitors, the sheer capacity advantage is obvious, and it explains why the car can deliver such relaxed performance without resorting to extreme boost pressures or sky-high rev limits. The fact that this 6.75 L twin-turbo V8 sits in a four-door body with a full suite of luxury appointments only strengthens the case that the Mulsanne occupies a unique niche in the market, one that is unlikely to be replicated as emissions rules tighten and electrification accelerates.
The final chapter for a colossal V8
As impressive as the Mulsanne’s engine is, its story is also about endings. Coverage from Dec 17, 2020, framed the farewell to the model as a goodbye not just to a car, but to the 6.75L V8 that defined it. That retrospective reflects on how enthusiasts, including writers who are self-confessed fans of mechanical detail, came to appreciate the quirks of this powertrain only as its production life was drawing to a close. The same piece notes that despite being an enthusiast of modern technology, the author found it hard to ignore the emotional pull of the V8 and the Mulsanne Speed, underlining how the 6.75L V8 and the Mulsanne Speed had become intertwined in the minds of fans.
From my perspective, that farewell crystallizes why the Mulsanne’s giant twin-turbo V8 matters beyond its raw numbers. It represents the end of a particular engineering era in which displacement and refinement were allowed to coexist at the very top of the luxury hierarchy, without the compromises that come with downsizing or heavy electrification. As Bentley pivots toward hybrid and fully electric flagships, the Mulsanne’s 6.75L V8 becomes a historical marker, a reminder that there was a time when a manufacturer could justify building a sedan around such a colossal combustion engine. The Dec coverage captures that sense of transition, and it helps explain why the car’s departure felt like a bigger moment than the retirement of a typical model line.
Why this engine still matters in 2025
Even with the Mulsanne out of production, the idea of a sedan hiding the largest twin-turbo V8 continues to resonate. The Nov 23, 2025, analysis that revisits the Bentley Mulsanne does so from the vantage point of a market increasingly dominated by electrified powertrains, which only makes the 6.75-Liter twin-turbo V8 seem more audacious. That piece underscores how the Bentley Mulsanne, with its Liter Twin Turbo configuration and its status as a huge and stately luxury sedan, now reads like a time capsule from a different automotive age. In a landscape where performance is often measured in kilowatts and battery capacity, the idea of a 6.75-Liter V8 quietly idling under a polished bonnet feels almost subversive, a point that the Nov coverage makes by revisiting the three-ton vehicle and its improbable acceleration.
For enthusiasts and historians alike, the Mulsanne’s engine has become a reference point in discussions about what we lose and gain as the industry evolves. On one hand, modern electric sedans can easily out-accelerate a Bentley Mulsanne while producing zero tailpipe emissions, and they do so with a different kind of silent effortlessness. On the other hand, the sensory experience of a 6.75-Liter twin-turbo V8, with its deep reserve of torque and its connection to six decades of Bentley engineering, is something that cannot be replicated by software updates or battery chemistry. When I look at the reporting that continues to spotlight the Bentley Mulsanne in 2025, I see a recognition that this car, and its vast twin-turbo V8, mark the end of a chapter in automotive history that is unlikely to be written again.
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