The Infiniti M56, produced from 2010 to 2019 as part of the fourth generation (Y51) of the Infiniti M series, represented a significant step upmarket for the brand. Positioned as the performance flagship of the M lineup, the M56 featured a naturally aspirated 5.6-liter V8 engine and standard all-wheel drive. It aimed to compete with established luxury sedans from European and domestic manufacturers, offering a blend of power, technology, and relative value. The Y51 generation, built on the Nissan FM platform, was a crucial model for Infiniti, showcasing their ambition to deliver a more refined and engaging driving experience.
Technical Specifications
| Brand | Infiniti |
| Model | M |
| Generation | M IV (Y51) |
| Type (Engine) | M56 V8 (420 Hp) AWD Automatic |
| Start of production | 2010 |
| End of production | 2019 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Sedan |
| Seats | 5 |
| Doors | 4 |
| Fuel consumption (urban) | 14.7 l/100 km (16 US mpg, 19.2 UK mpg) |
| Fuel consumption (extra urban) | 10.2 l/100 km (23.1 US mpg, 27.7 UK mpg) |
| Fuel Type | Petrol (Gasoline) |
| Weight-to-power ratio | 4.6 kg/Hp, 219.2 Hp/tonne |
| Weight-to-torque ratio | 3.4 kg/Nm, 294.9 Nm/tonne |
| Power | 420 Hp @ 6000 rpm |
| Power per litre | 75.6 Hp/l |
| Torque | 565 Nm @ 4400 rpm (416.72 lb.-ft. @ 4400 rpm) |
| Maximum engine speed | 6700 rpm |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | VK56VD |
| Engine displacement | 5552 cm3 (338.8 cu. in.) |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 98 mm (3.86 in.) |
| Piston Stroke | 92 mm (3.62 in.) |
| Compression ratio | 11.5:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Direct injection |
| Valvetrain | DOHC |
| Engine oil capacity | 6.1 l (6.45 US qt | 5.37 UK qt) |
| Coolant capacity | 10.9 l (11.52 US qt | 9.59 UK qt) |
| Kerb Weight | 1916 kg (4224.06 lbs.) |
| Max. weight | 2395 kg (5280.07 lbs.) |
| Max load | 479 kg (1056.01 lbs.) |
| Trunk (boot) space (minimum) | 422 l (14.9 cu. ft.) |
| Fuel tank capacity | 76 l (20.08 US gal | 16.72 UK gal) |
| Length | 4945 mm (194.69 in.) |
| Width | 1844 mm (72.6 in.) |
| Height | 1514 mm (59.61 in.) |
| Wheelbase | 2901 mm (114.21 in.) |
| Front track | 1575 mm (62.01 in.) |
| Rear track | 1565 mm (61.61 in.) |
| Ride height (ground clearance) | 145 mm (5.71 in.) |
| Drag coefficient (Cd) | 0.27 |
| Minimum turning circle | 11.4 m (37.4 ft.) |
| Drivetrain Architecture | All wheel drive (4×4). ICE drives rear wheels, front wheels engaged via clutch. |
| Number of gears | 7 |
| Gearbox type | Automatic transmission |
| Front suspension | Double wishbone |
| Rear suspension | Independent multi-link with stabilizer |
| Front brakes | Ventilated discs, 320.04×27.94 mm |
| Rear brakes | Ventilated discs, 307.34×15.24 mm |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Steering rack and pinion |
| Power steering | Electric |
| Tires size | 245/50 R18 V |
| Wheel rims size | 8.0J x 18 |
Powertrain & Engine Architecture
The heart of the M56 is the VK56VD 5.6-liter V8 engine. This engine is a naturally aspirated powerplant featuring Nissan’s Variable Valve Event and Lift (VVEL) technology, along with direct fuel injection. VVEL allows for continuously variable control of valve timing and lift, optimizing engine performance and efficiency across a wider range of engine speeds. The engine utilizes a dual overhead camshaft (DOHC) design with four valves per cylinder. The VK56VD produces 420 horsepower at 6000 rpm and 417 lb-ft of torque at 4400 rpm. This power is delivered to all four wheels through a seven-speed automatic transmission. The transmission is designed for smooth and responsive shifting, with manual shift mode available for driver control. The all-wheel-drive system is primarily rear-biased, enhancing the sporty driving dynamics.
Driving Characteristics
The M56’s combination of a powerful V8 and all-wheel drive results in confident acceleration and handling. While not as overtly sporty as some of its European rivals, the M56 offers a comfortable and refined driving experience. The seven-speed automatic transmission provides smooth gear changes, and the rear-biased all-wheel-drive system contributes to a balanced feel. Compared to the M37 (with its 3.7-liter V6), the M56 delivers significantly more torque, resulting in stronger acceleration, particularly in highway passing situations. The M56’s weight, however, does slightly diminish its agility compared to lighter, rear-wheel-drive competitors. The gear ratios are tuned for a balance between performance and fuel economy, prioritizing smooth cruising over aggressive acceleration.
Equipment & Trim Levels
The M56 typically came well-equipped, reflecting its position as the top-of-the-line M model. Standard features included leather upholstery, heated and ventilated front seats, a premium Bose audio system, a navigation system, and a suite of advanced safety technologies. Available options included a rear-seat entertainment system, adaptive cruise control, lane departure warning, and blind-spot monitoring. Interior trim options typically included wood or aluminum accents. The dashboard layout is driver-focused, with a clear and intuitive infotainment system. The M56’s interior aimed to provide a luxurious and comfortable environment for both driver and passengers.
Chassis & Braking
The Y51 M-series utilizes a double wishbone front suspension and an independent multi-link rear suspension, both incorporating stabilizer bars to reduce body roll. The M56 featured larger brakes compared to lower trims, with ventilated discs at all four corners. Front brakes measured 320mm in diameter, while rear brakes were 307mm. The braking system is assisted by ABS (Anti-lock Braking System) and electronic brake-force distribution. The suspension tuning is geared towards comfort and stability, providing a smooth ride over various road surfaces. The all-wheel-drive system contributes to enhanced traction and stability, particularly in inclement weather.
Market Reception & Comparison
The Infiniti M56 was generally well-received by automotive critics, who praised its powerful engine, comfortable ride, and generous standard features. However, some reviewers noted that its styling was somewhat conservative compared to its European competitors. Fuel economy was also a point of criticism, as the 5.6-liter V8 is inherently less efficient than smaller engines. Compared to the M37, the M56 offered a significant performance upgrade but came at a higher price point. Against rivals like the BMW 550i and the Mercedes-Benz E550, the M56 offered a compelling value proposition, providing similar levels of performance and luxury at a lower cost.
Legacy
The VK56VD engine, while not known for any major inherent flaws, requires regular maintenance to ensure longevity. Common issues include oil consumption and potential for carbon buildup on the intake valves, typical for direct-injection engines. The seven-speed automatic transmission is generally reliable, but fluid changes should be performed according to the manufacturer’s recommendations. Today, the Infiniti M56 represents a relatively affordable entry point into the luxury V8 sedan market. Its combination of power, comfort, and features makes it an attractive option for buyers seeking a spacious and capable grand tourer. While not as sought-after as some of its European rivals, the M56 has developed a loyal following among enthusiasts who appreciate its unique blend of Japanese engineering and American V8 muscle.
