The Bentley Mulsanne is a full-size luxury car that was manufactured and marketed by British automaker Bentley Motors from March 2010 to June 2020. It was the flagship automobile for the company during its production run. Internal to Bentley, the Mulsanne was referred to as "The Grand Bentley" during its development.

Replacing the Rolls-Royce-based Arnage, the Mulsanne was Bentley's first independently-built automobile since the 8 Litre, which W. O. Bentley conceived. Unveiled initially at the Pebble Beach Concours d'Elegance, the Mulsanne retained two key elements from the Arnage—rear-wheel drive with the front axle centerline optimally positioned forward, and a 6.75-litre push-rod V8 engine equipped with twin-turbochargers. The individualistic headlamps were designed to resemble those of the Jaguar S-Type from the 1960s. Throughout its ten-year manufacturing period, Bentley produced approximately 7,900 examples at the Crewe facility. The Mulsanne has generally been well received, with Jeremy Clarkson claiming that the ride is quiet and the torques were great while criticising the number of switches and the fact that it was less "tasteful" than a Rolls-Royce Ghost.

In 2005, development work on the Mulsanne officially commenced under the codename "Project Kimberley", the name of which was inspired by the Kimberley diamond originating from South Africa. Styled by Belgian automobile designer Dirk van Braeckel, the Mulsanne is a four-door sedan which was offered in two body lengths: short- and extended-wheelbase. Incorporating various internal and external elements from the Arnage, it employs a blend of high-strength steel and lightweight aluminium. The team that assembles the Mulsanne is composed of 298 Bentley employees. The interior was designed under the direction of British automobile designer Robin Page, who also led that of the second-generation Continental GT. Each individual unit undergoes a meticulous process that takes 400 hours (2 weeks), of which 136 hours (five days) are dedicated to interior trimming.

Production of the Mulsanne concluded on 25 June 2020, signifying not only the end of its ten-year manufacture but also the end of Bentley's 6¾-litre engine after a consecutive 61-year production period. The 6¾-litre V8 engine, introduced in 1959 and heavily revised and updated in 2010, could not be updated any further to meet the increasingly stringent emission regulations, namely emissions. No replacement for either Mulsanne or 6¾-litre V8 engine is planned. Instead, the third generation Flying Spur would succeed the Mulsanne as Bentley's flagship model.

History

2005–2009: Development and design The development and design phase of the forthcoming flagship began in June 2005, with initial design concepts written at the Bentley Design studio in Crewe. Developed under the internal codename "Project Kimberley", the name of which was inspired by a diamond found in South Africa, the Mulsanne project represented Bentley's first independently designed and developed car since W. O. Bentley's conception of the 8 Litre in 1930. The car was also the company's first model developed wholly at the Crewe design facility. The inception of the Mulsanne was an unforeseen project, as efforts were initially focused on preserving the Arnage following Volkswagen Group's acquisition of Bentley. At that juncture, there was neither a formalised strategy nor sufficient funding for the replacement of Bentley's flagship with an entirely new vehicle. Originally, the upcoming Continental Flying Spur was slated as the successor, but dissatisfaction with this concept prompted Bentley chairman Franz-Josef Paefgen to abruptly discontinue it. He advocated for the development of an entirely new vehicle, preserving two integral elements of the Arnage's design: rear-wheel drive with the front axle centreline optimally positioned forward, and a 6.75-litre push-rod V8 with a twin-turbo system.

In the winter of 2005, three design concepts were selected and transformed into digital form. Alias models were then created, and one-third-scale clay models were milled from the three designs. A presentation to the Bentley board in March 2006 led to two proposals being chosen for full-scale clay models, with the final design freeze occurring in winter 2007. The design team, including senior designer Crispin Marshfield, designer Gareth Thomas, and junior designer Vitalis Enns, spent a year refining the design through a combination of clay and digital iterations. Hand clay modelling was crucial for achieving the desired sculptural quality. Extensive work in CFG and the wind tunnel, along with input from suppliers, led to design tweaks and the creation of full-size GKN data control models. The final selection process by the board in September 2007 resulted in a design freeze, with the two full-scale clays sharing similar features like a shallow V-shaped hood and distinctive locomotive-style shoulders inherited from the 2008 Brooklands coupe.

Throughout its development, one of the team's goals was to construct a heavy vehicle, as part of Bentley's philosophy that the weight of a car is intrinsically linked to its identity, as perceived by customers. Bentley believed that a lighter vehicle would "spoil the driving experience," which British magazine Evo described as a "strange thing to hear from a car company these days". Nevertheless, Paefgen instructed engineers not to surpass the kerb weight of the preceding Arnage. The exterior styling was overseen by a team directed by Belgian designer Dirk van Braeckel, who articulated that the styling drew inspiration from the tradition of historical grand touring Bentleys. Van Braeckel stated that, "from the very first-hand sketches in the styling studio [...] we have sought to evolve this story for a new generation of Bentley enthusiasts". Heading the interior design was British designer Robin Page, who also supervised that of the second-generation Continental GT. Despite being a new model developed and engineered wholly at the Bentley Crewe facility, its engine, the 6¾-litre unit developed with Rolls-Royce, was predominantly carried over from the Arnage. However, modifications were implemented to reduce weight, increase horsepower, and optimise fuel efficiency. The engine revision resulted in a weight loss of by using a new crankshaft, per piston and per conrod. The pistons and gudgeon pins received a coating of diamond-like carbon (DLC), and the piston skirts were coated with graphite. These coatings served to minimise friction and fuel consumption, while also optimising the durability of the components under high engine loads.

2009–2010: Launch Before the launch of the 2009 model, the Mulsanne designation was most recently employed by Bentley to denote a four-door saloon manufactured from 1980 to 1992. Subsequently, it was reinstated as the nomenclature for the successor to the Arnage, which served as Bentley's flagship model at the time. It made its first appearance at the Pebble Beach Concours d'Elegance in 2009, its second at the 2009 Frankfurt Motor Show, its third at the 2010 North American International Auto Show, and its fourth and final at the 2012 Qatar Motor Show. The first Mulsanne produced, with chassis number 00001, was sold in 2009 at the Gooding & Company Pebble Beach auction for US$500,000 (US$550,000 after buyer premium) to an undisclosed bidder. Deliveries in England began in September 2010.

Assembly Each individual Mulsanne is hand-built and undergoes a meticulous process spanning approximately 200 hours (16 days). A total of 298 employees are dedicated to each unit, with the collective effort of about 4,000 employees contributing to the completion of all 7,300 Mulsannes. The assembly area covers an extensive , serving as the centre for all aspects of car production. This includes design, research and development, engineering, manufacturing, quality control, as well as operations related to sales and marketing. The first stage of the Mulsanne's assembly process involves its body in white, where Bentley metalworkers perform 5,800 individual welds, joining hundreds of meters of steel and aluminium. Bentley's objective was to render all traces of welds entirely imperceptible, creating the illusion that the body seamlessly originated from a single piece of metal. In specific areas, such as where the roof merges into the rear haunch through the deep D-pillar, a team brazes the joint by hand until it becomes entirely invisible to the human eye, particularly once the vehicle is painted. Customers are offered a choice from a palette of over 120 exterior paint colours from Bentley, or they can opt to create a custom colour, matching it to a precious object if desired. Due to the body's curvature, the paint application requires precise hand spraying at various depths to achieve a smooth and even appearance. Following the lacquering process, each car undergoes fine sanding and is polished with lamb's wool for 12 hours, resulting in a reflective finish, dubbed by Bentley as the "Mirror Finish".

Wood plays a crucial role, forming a foundation of solid walnut, cherry, or oak that runs through the dashboard and doors of the Mulsanne. Exclusive to this model, a solid wood substrate is overlaid with a selection of a dozen different veneers, sourced from sustainable origins globally, with colours ranging from red to brown and black. These veneers often come from century-old exotic trees, including vavona from the US, madrona from the US, olive ash from Europe and Southwest Asia, tamo ash from China, or birds-eye maple from North America. Customers were progressively shifting from curly wood grains to straight grains like eucalyptus from Australia and Spain, koa from or liquid amber from the US. Stone veneers from stone mined in India, formed over 200 million years ago, are often used. Each sheet of wood, derived from the same tree, undergoes a process where the root burl is steamed and cut into slices. This ensures that the pattern and colour remain consistent throughout the entire car and age uniformly. Laser-cut veneers are mirror-matched to create 33 separate components. Following sanding, each part receives five layers of lacquer, undergoes a 72-hour curing process, is then sanded and polished again before being fitted to the car.

The Mulsanne undergoes a hand-assembly process in a dedicated build area staffed by 120 employees, distinct from the main assembly hall operating lines for the Bentayga, Continental GT, and Flying Spur models. This intricate process involves connecting , wiring looms, fitting dashboards and steering wheels, marrying engines, adding brake fluids and coolants, assembling matrix grills with front fenders, attaching wheels, bonding windscreens, and installing doors and seats. Every artisan working on a Mulsanne must memorise and possess the skills to complete over 6.5 work hours on the car. With a production rate of nine cars per week, the Mulsanne production line comprises 12 workstations fed by seven sub-assembly/trim areas. Each workstation spends 203 minutes per car, compared to the nine minutes per station for the Continental GT. The Mulsanne is manually moved along the production line. Following this assembly, each vehicle undergoes a visual inspection for quality against a 500 to 650-point checklist before receiving final sign-off.

Design and features