The Infiniti FX 45 (facelift, 2006) represented the pinnacle of performance within the first generation FX series (2003-2008). Equipped with the VK45DE 4.5-liter V8 engine producing 328 horsepower and paired with a 5-speed automatic transmission and all-wheel drive, this variant was produced from 2006 through 2008. The 2006 facelift brought styling updates and minor mechanical refinements to Infiniti’s luxury crossover. This model aimed to deliver a blend of luxury, performance, and all-weather capability, positioning itself as a competitor to European performance SUVs like the Porsche Cayenne and BMW X5, but with a distinctly Japanese approach to refinement and technology.
Technical Specifications
| Brand | Infiniti |
| Model | FX |
| Generation | FX I (facelift 2006) |
| Type (Engine) | 45 V8 32V (328 Hp) AWD |
| Start of production | 2006 |
| End of production | 2008 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Crossover |
| Seats | 5 |
| Doors | 5 |
| Fuel consumption (urban) | 15.7 l/100 km (15 US mpg, 18 UK mpg, 6.4 km/l) |
| Fuel consumption (extra urban) | 12.4 l/100 km (19 US mpg, 22.8 UK mpg, 8.1 km/l) |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 6.3 sec |
| Acceleration 0 – 62 mph | 6.3 sec |
| Acceleration 0 – 60 mph | 6 sec |
| Maximum speed | 225 km/h (139.81 mph) |
| Weight-to-power ratio | 6.1 kg/Hp, 163.6 Hp/tonne |
| Weight-to-torque ratio | 4.5 kg/Nm, 222.9 Nm/tonne |
| Power | 328 Hp @ 6000 rpm |
| Power per litre | 73 Hp/l |
| Torque | 447 Nm @ 4000 rpm (329.69 lb.-ft. @ 4000 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | VK45DE |
| Engine displacement | 4494 cm3 (274.24 cu. in.) |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 93 mm (3.66 in.) |
| Piston Stroke | 82.7 mm (3.26 in.) |
| Compression ratio | 10.5:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Multi-port manifold injection |
| Engine aspiration | Naturally aspirated engine |
| Engine oil capacity | 5.8 l (6.13 US qt | 5.1 UK qt) |
| Coolant capacity | 10 l (10.57 US qt | 8.8 UK qt) |
| Kerb Weight | 2005 kg (4420.27 lbs.) |
| Max. weight | 2478 kg (5463.05 lbs.) |
| Max load | 473 kg (1042.79 lbs.) |
| Trunk (boot) space – minimum | 776 l (27.4 cu. ft.) |
| Trunk (boot) space – maximum | 1826 l (64.48 cu. ft.) |
| Fuel tank capacity | 90 l (23.78 US gal | 19.8 UK gal) |
| Length | 4803 mm (189.09 in.) |
| Width | 1925 mm (75.79 in.) |
| Height | 1674 mm (65.91 in.) |
| Wheelbase | 2850 mm (112.2 in.) |
| Front track | 1593 mm (62.72 in.) |
| Rear (Back) track | 1640 mm (64.57 in.) |
| Drive wheel | All wheel drive (4×4) |
| Number of gears and type of gearbox | 5 gears, automatic transmission |
| Front suspension | Independent, type McPherson with coil spring and anti-roll bar |
| Rear suspension | Independent multi-link spring suspension with stabilizer |
| Front brakes | Disc |
| Rear brakes | Disc |
| Assisting systems | ABS (Anti-lock braking system) |
| Tires size | 265/50 R20 |
Powertrain & Engine Architecture
The 2006 Infiniti FX 45 is powered by the VK45DE, a 4.5-liter naturally aspirated V8 engine. This engine features a 32-valve design with dual overhead camshafts (DOHC) and continuously variable valve timing (CVVT) on both the intake and exhaust valves. The VK45DE utilizes a multi-port fuel injection system, delivering fuel directly into each intake port. The engine’s architecture prioritizes smooth power delivery and refinement, hallmarks of Japanese engineering. The 5-speed automatic transmission, designated the 5AT, is a conventional torque converter automatic. While it doesn’t offer the rapid shifts of some contemporary dual-clutch transmissions, it emphasizes smoothness and reliability. The all-wheel-drive system employs a viscous coupling to distribute torque between the front and rear axles, enhancing traction in various conditions.
Driving Characteristics
The FX 45’s 328 horsepower and 329 lb-ft of torque deliver brisk acceleration, with 0-60 mph times around 6 seconds. The automatic transmission, while smooth, isn’t aggressively programmed, resulting in a more relaxed driving experience compared to sportier, manual-transmission SUVs. The AWD system provides confident handling in inclement weather, but the FX 45’s weight (over 4,400 lbs) limits its agility compared to lighter crossovers. The gear ratios are tuned for a balance of acceleration and highway cruising, with the fifth gear offering quiet operation at higher speeds. Compared to the FX 35 (with its 3.5L V6), the FX 45 offers significantly more power and torque, providing a more effortless driving experience, especially when fully loaded or towing.
Equipment & Trim Levels
The 2006 Infiniti FX 45 came standard with a comprehensive list of features, including leather upholstery, power-adjustable heated front seats, a Bose premium sound system, a sunroof, and automatic climate control. Available options included a navigation system, rear-seat DVD entertainment, and adaptive cruise control. The interior design emphasizes luxury and comfort, with high-quality materials and a user-friendly layout. Exterior features included alloy wheels, fog lights, and a rear spoiler. The FX 45 represented the highest trim level, offering all available features and the most powerful engine option.
Chassis & Braking
The FX 45 utilizes an independent suspension system at all four corners. The front suspension employs a McPherson strut design with coil springs and an anti-roll bar, while the rear suspension features a multi-link setup with coil springs and a stabilizer bar. This configuration aims to provide a comfortable ride while maintaining reasonable handling. Brakes consist of ventilated discs on all four wheels, with ABS (Anti-lock Braking System) as standard equipment. The braking system is adequate for the vehicle’s weight and performance, but lacks the aggressive bite of some high-performance systems.
Market Reception & Comparison
Critics generally praised the Infiniti FX 45 for its powerful engine, luxurious interior, and comfortable ride. However, some reviewers noted its relatively high fuel consumption (15 mpg city / 19 mpg highway) and considerable weight. Compared to the FX 35, the FX 45 offered a significant performance advantage, but at a higher price. The FX 45’s fuel economy was comparable to other V8-powered SUVs of the time, but lagged behind more fuel-efficient V6 options. Reliability was generally good, although some owners reported minor issues with the electronic systems.
Legacy
The Infiniti FX 45 (2006-2008) remains a desirable vehicle in the used car market, particularly for those seeking a blend of luxury, performance, and all-weather capability. The VK45DE engine is known for its durability and relatively straightforward maintenance. While not as technologically advanced as newer SUVs, the FX 45 offers a unique driving experience and a distinctive styling that has aged well. Common maintenance items include regular oil changes, coolant flushes, and inspection of the suspension components. The 5-speed automatic transmission has proven generally reliable, but may require servicing at higher mileage. Overall, the FX 45 represents a solid and well-built SUV that continues to provide years of reliable service.
