The Jaguar XJ Sovereign (X358) 4.2 V8 Automatic, produced between 2007 and 2009, represents a significant evolution of Jaguar’s flagship sedan. Falling within the third generation (X358) of the XJ line, this variant occupied a premium position in the range, offering a blend of luxury, performance, and technology. The X358 generation itself was a substantial refresh of the X350, addressing criticisms regarding its styling and interior. This particular 4.2 V8 Automatic model aimed to deliver a refined driving experience, appealing to buyers seeking a powerful yet comfortable grand tourer. It was positioned above the base 3.0L models and below the supercharged 4.2 V8, offering a sweet spot in terms of performance and price.
Technical Specifications
| Brand | Jaguar |
| Model | XJ |
| Generation | XJ Sovereign (X358) |
| Type (Engine) | 4.2 V8 (298 Hp) Automatic |
| Start of production | 2007 |
| End of production | 2009 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Sedan |
| Seats | 5 |
| Doors | 4 |
| Fuel consumption (economy) – urban (NEDC) | 16.7 l/100 km (14.1 US mpg, 16.9 UK mpg, 6 km/l) |
| Fuel consumption (economy) – extra urban (NEDC) | 8.4 l/100 km (28 US mpg, 33.6 UK mpg, 11.9 km/l) |
| Fuel consumption (economy) – combined (NEDC) | 11.4 l/100 km (20.6 US mpg, 24.8 UK mpg, 8.8 km/l) |
| CO2 emissions (NEDC) | 269 g/km |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 6.6 sec |
| Acceleration 0 – 62 mph | 6.6 sec |
| Acceleration 0 – 60 mph | 6.3 sec |
| Maximum speed | 250 km/h (155.34 mph), Electronically limited |
| Emission standard | Euro 4 |
| Weight-to-power ratio | 5.4 kg/Hp, 185.2 Hp/tonne |
| Weight-to-torque ratio | 3.9 kg/Nm, 255.4 Nm/tonne |
| Power | 298 Hp @ 6000 rpm |
| Power per litre | 71 Hp/l |
| Torque | 411 Nm @ 4100 rpm (303.14 lb.-ft. @ 4100 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | AJ34 |
| Engine displacement | 4196 cm3 (256.06 cu. in.) |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 86 mm (3.39 in.) |
| Piston Stroke | 90.3 mm (3.56 in.) |
| Compression ratio | 11:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Multi-port manifold injection |
| Engine aspiration | Naturally aspirated engine |
| Valvetrain | DOHC |
| Engine oil capacity | 6 l (6.34 US qt | 5.28 UK qt) |
| Coolant | 9.45 l (9.99 US qt | 8.31 UK qt) |
| Kerb Weight | 1609 kg (3547.24 lbs.) |
| Max. weight | 2246 kg (4951.58 lbs.) |
| Max load | 637 kg (1404.34 lbs.) |
| Trunk (boot) space – minimum | 470 l (16.6 cu. ft.) |
| Fuel tank capacity | 85 l (22.45 US gal | 18.7 UK gal) |
| Max. roof load | 75 kg (165.35 lbs.) |
| Permitted trailer load with brakes (12%) | 1900 kg (4188.78 lbs.) |
| Permitted trailer load without brakes | 750 kg (1653.47 lbs.) |
| Permitted towbar download | 75 kg (165.35 lbs.) |
| Length | 5216 mm (205.35 in.) |
| Width | 1860 mm (73.23 in.) |
| Width with mirrors folded | 1898 mm (74.72 in.) |
| Width including mirrors | 2104 mm (82.83 in.) |
| Height | 1463 mm (57.6 in.) |
| Wheelbase | 3159 mm (124.37 in.) |
| Front track | 1556 mm (61.26 in.) |
| Rear (Back) track | 1546 mm (60.87 in.) |
| Drag coefficient (Cd) | 0.32 |
| Minimum turning circle (turning diameter) | 12.04 m (39.5 ft.) |
| Drivetrain Architecture | The Internal combustion engine (ICE) drives the rear wheels of the vehicle. |
| Drive wheel | Rear wheel drive |
| Number of gears and type of gearbox | 6 gears, automatic transmission |
| Front suspension | Double wishbone, Transverse stabilizer |
| Rear suspension | Double wishbone, Transverse stabilizer |
| Front brakes | Ventilated discs |
| Rear brakes | Ventilated discs |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Steering rack and pinion |
| Power steering | Hydraulic Steering |
| Tires size | 255/40 HR19 |
| Wheel rims size | 8.5J x 19 |
Powertrain & Engine Architecture
At the heart of the XJ Sovereign 4.2 V8 Automatic lies the AJ34 engine, a naturally aspirated 4.2-liter V8. This engine, a cornerstone of Jaguar’s powertrain lineup during this period, is characterized by its smooth power delivery and distinctive exhaust note. The AJ34 utilizes multi-port fuel injection and a double overhead camshaft (DOHC) valvetrain, contributing to its responsive nature. The engine produces 298 horsepower at 6000 rpm and 411 Nm (303 lb-ft) of torque at 4100 rpm. The engine’s architecture is longitudinal, meaning it’s mounted with the crankshaft running front to back, and drives the rear wheels. Paired with the engine is a six-speed automatic transmission, providing smooth shifts and contributing to the car’s overall refinement. This transmission was designed to balance performance with fuel efficiency, although the XJ 4.2 V8 was never intended to be a fuel miser.
Driving Characteristics
The 4.2 V8 Automatic XJ delivers a distinctly grand touring experience. While not as overtly sporty as the supercharged variants, the 298 hp engine provides ample power for effortless cruising and confident overtaking. The six-speed automatic transmission is well-tuned, offering smooth and relatively quick shifts. Acceleration from 0-60 mph takes approximately 6.3 seconds, and the car is electronically limited to a top speed of 155 mph. The automatic transmission’s gear ratios are geared towards comfort and refinement, prioritizing smooth transitions over aggressive downshifts. Compared to the manual transmission options available on other XJ models, the automatic prioritizes ease of use and a more relaxed driving experience. It lacks the direct engagement offered by a manual, but compensates with its seamless operation.
Equipment & Trim Levels
The XJ Sovereign trim level included a generous array of standard features. Interior appointments typically included leather upholstery, wood veneer trim, and a premium audio system. Standard equipment also included automatic climate control, power-adjustable seats with memory function, and a sunroof. Optional extras included upgraded leather options, rear seat entertainment systems, and advanced navigation systems. The Sovereign trim aimed to provide a luxurious and comfortable environment for both driver and passengers.
Chassis & Braking
The XJ Sovereign 4.2 V8 utilizes a double wishbone suspension system at both the front and rear, incorporating a transverse stabilizer bar to minimize body roll. This suspension setup provides a comfortable ride while maintaining reasonable handling characteristics. Braking duties are handled by ventilated discs on all four wheels, coupled with an Anti-lock Braking System (ABS) for enhanced safety. The XJ’s chassis is designed to provide a balance between rigidity and weight, contributing to its overall stability and handling.
Market Reception & Comparison
The XJ Sovereign 4.2 V8 Automatic was generally well-received by automotive critics. It was praised for its luxurious interior, smooth ride, and powerful engine. However, its fuel economy was often cited as a drawback, typical for a large V8-powered sedan. Compared to the base 3.0L models, the 4.2 V8 offered a significant performance upgrade, justifying its higher price tag. Against the supercharged 4.2 V8, it represented a more sensible option for buyers who didn’t require the ultimate in performance. Reliability was generally good, although preventative maintenance was crucial to avoid potential issues with the engine’s timing chain tensioners.
Legacy
The Jaguar XJ Sovereign 4.2 V8 Automatic remains a desirable used car today, particularly for enthusiasts seeking a classic British luxury sedan. The AJ34 engine, while requiring regular maintenance, is generally considered robust. Common issues include oil leaks and potential problems with the timing chain tensioners, but these are often addressed with preventative maintenance. The XJ’s blend of luxury, performance, and timeless styling ensures its continued appeal in the used car market. It represents a high point in Jaguar’s engineering and design, offering a refined and rewarding driving experience.
