The Citroen C4 I Hatchback, specifically the Phase II model produced between 2008 and 2010, represented a significant evolution of Citroen’s compact family car. Within the C4 I generation (produced from 2004-2010), the Phase II facelift brought styling updates and, crucially, the introduction of the 1.6 THP 16V engine, a turbocharged petrol unit offering a blend of performance and efficiency. This 150 horsepower variant occupied a mid-range position in the C4 lineup, slotting above the naturally aspirated 1.4 and 1.6-liter engines and below the more potent 2.0-liter HDi diesel options. It was aimed at buyers seeking a more engaging driving experience than the base models, without the higher running costs associated with the diesel or the top-tier petrol engines.
Technical Specifications
| Brand | Citroen |
| Model | C4 |
| Generation | C4 I Hatchback (Phase II, 2008) |
| Type (Engine) | 1.6 THP 16V (150 Hp) |
| Start of production | 2008 |
| End of production | 2010 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Hatchback |
| Seats | 5 |
| Doors | 5 |
| Fuel consumption (urban) | 9.8 l/100 km (24 US mpg, 28.8 UK mpg, 10.2 km/l) |
| Fuel consumption (extra urban) | 5.3 l/100 km (44.4 US mpg, 53.3 UK mpg, 18.9 km/l) |
| Fuel consumption (combined) | 6.9 l/100 km (34.1 US mpg, 40.9 UK mpg, 14.5 km/l) |
| CO2 emissions | 164 g/km |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 8.4 sec |
| Acceleration 0 – 62 mph | 8.4 sec |
| Acceleration 0 – 60 mph | 8 sec (Calculated) |
| Maximum speed | 211 km/h (131.11 mph) |
| Emission standard | Euro 4 |
| Weight-to-power ratio | 8.5 kg/Hp, 117.6 Hp/tonne |
| Weight-to-torque ratio | 5.3 kg/Nm, 188.1 Nm/tonne |
| Power | 150 Hp @ 5800 rpm |
| Power per litre | 93.9 Hp/l |
| Torque | 240 Nm @ 1400 rpm (177.01 lb.-ft. @ 1400 rpm) |
| Engine layout | Front, Transverse |
| Engine Model/Code | 5FX EP6DT |
| Engine displacement | 1598 cm3 (97.52 cu. in.) |
| Number of cylinders | 4 |
| Engine configuration | Inline |
| Cylinder Bore | 77 mm (3.03 in.) |
| Piston Stroke | 85.8 mm (3.38 in.) |
| Compression ratio | 11:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Multi-port manifold injection |
| Engine aspiration | Turbocharger, Intercooler |
| Valvetrain | DOHC |
| Engine oil capacity | 4.25 l (4.49 US qt, 3.74 UK qt) |
| Coolant capacity | 6.2 l (6.55 US qt, 5.46 UK qt) |
| Kerb Weight | 1276 kg (2813.1 lbs.) |
| Max. weight | 1763 kg (3886.75 lbs.) |
| Max load | 487 kg (1073.65 lbs.) |
| Trunk (boot) space – minimum | 320 l (11.3 cu. ft.) |
| Trunk (boot) space – maximum | 1023 l (36.13 cu. ft.) |
| Fuel tank capacity | 60 l (15.85 US gal, 13.2 UK gal) |
| Max. roof load | 75 kg (165.35 lbs.) |
| Permitted trailer load with brakes (8%) | 1500 kg (3306.93 lbs.) |
| Permitted trailer load with brakes (12%) | 1400 kg (3086.47 lbs.) |
| Permitted trailer load without brakes | 645 kg (1421.98 lbs.) |
| Permitted towbar download | 70 kg (154.32 lbs.) |
| Length | 4275 mm (168.31 in.) |
| Width | 1773 mm (69.8 in.) |
| Width including mirrors | 1964 mm (77.32 in.) |
| Height | 1496 mm (58.9 in.) |
| Wheelbase | 2608 mm (102.68 in.) |
| Front track | 1505 mm (59.25 in.) |
| Rear track | 1510 mm (59.45 in.) |
| Front overhang | 950 mm (37.4 in.) |
| Rear overhang | 717 mm (28.23 in.) |
| Drag coefficient (Cd) | 0.31 |
| Minimum turning circle | 11.3 m (37.07 ft.) |
| Drivetrain Architecture | Front wheel drive |
| Number of gears | 6 |
| Gearbox type | Manual transmission |
| Front suspension | Independent, McPherson with coil spring and anti-roll bar |
| Rear suspension | Semi-independent, coil spring |
| Front brakes | Ventilated discs |
| Rear brakes | Disc |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Steering rack and pinion |
| Tires size | 205/50 R17 |
| Wheel rims size | 17 |
INTRODUCTION
The Citroen C4 I Phase II 1.6 THP 16V (150 Hp) was a key component of Citroen’s strategy to offer a more modern and appealing compact hatchback. Introduced in 2008, it benefited from the Phase II revisions to the C4, which included subtle styling changes and improvements to the interior. The 1.6 THP engine, co-developed with BMW, was a significant upgrade over the older naturally aspirated engines previously offered, providing a noticeable boost in performance and a more refined driving experience. This variant aimed to attract customers who desired a balance between fuel economy, performance, and modern features.
Powertrain & Engine Architecture
The heart of this C4 variant is the 5FX (EP6DT) 1.6-liter turbocharged petrol engine. This engine is part of the Prince engine family, a collaborative effort between PSA Peugeot Citroen and BMW. It features direct fuel injection, a variable valve timing system on both intake and exhaust valves (DOHC), and a single scroll turbocharger with an intercooler. The direct injection system, operating at pressures up to 120 bar, ensures precise fuel delivery for optimal combustion and efficiency. The engine’s 16 valves contribute to its responsive nature. The 150 horsepower output is achieved at 5800 rpm, while the peak torque of 240 Nm (177 lb-ft) is available from a low 1400 rpm, providing strong pulling power across a wide rev range. The engine is typically paired with a 6-speed manual transmission, although an automatic transmission was also available, albeit less common. The automatic transmission is a conventional torque converter type, offering smooth shifts but slightly impacting fuel economy compared to the manual.
Driving Characteristics
The 1.6 THP 16V equipped C4 offers a noticeably more spirited driving experience than its lower-powered siblings. The turbocharger provides a surge of power in the mid-range, making overtaking and merging onto highways effortless. Acceleration from 0-100 km/h (0-62 mph) takes around 8.4 seconds, which was competitive for its class at the time. The 6-speed manual transmission allows drivers to fully exploit the engine’s powerband, while the automatic provides convenience in urban driving. The gear ratios are well-chosen, providing a balance between acceleration and fuel efficiency. Compared to the 2.0-liter HDi diesel, the 1.6 THP offers a more responsive and engaging driving experience, but sacrifices some fuel economy. Compared to the naturally aspirated 1.6, the turbocharger provides a significant performance advantage.
Equipment & Trim Levels
The 1.6 THP 16V variant was typically offered in mid-range trim levels, such as ‘Exclusive’ or ‘Sensium’ depending on the market. Standard equipment generally included air conditioning, power windows, central locking, a CD stereo with MP3 compatibility, and alloy wheels. Higher trim levels added features like automatic climate control, rain-sensing wipers, rear parking sensors, and a trip computer. Interior upholstery was typically cloth, with options for leather upgrades. Safety features included ABS, electronic brakeforce distribution (EBD), and front and side airbags. Optional extras included a panoramic sunroof, navigation system, and upgraded audio systems.
Chassis & Braking
The C4 I utilizes a McPherson strut front suspension and a semi-independent torsion beam rear suspension. This setup provides a comfortable ride quality while maintaining reasonable handling characteristics. The front suspension incorporates an anti-roll bar to reduce body roll during cornering. Braking duties are handled by ventilated discs at the front and solid discs at the rear. ABS (Anti-lock Braking System) is standard, enhancing braking performance and stability. The steering is rack and pinion, providing precise and responsive steering feel.
Market Reception & Comparison
The Citroen C4 I 1.6 THP 16V was generally well-received by automotive critics. It was praised for its responsive engine, comfortable ride, and well-equipped interior. However, some critics noted that the automatic transmission could feel slightly sluggish at times. Fuel economy was considered good for a petrol engine of this performance level, averaging around 6.9 l/100 km (34.1 US mpg). Compared to the diesel models, the 1.6 THP offered a more enjoyable driving experience but at the cost of slightly higher fuel consumption. Reliability was generally good, although some early examples of the 1.6 THP engine were known to experience issues with carbon buildup on the intake valves, requiring periodic cleaning.
Legacy
The 1.6 THP engine proved to be a successful powerplant for Citroen and Peugeot, appearing in a wide range of models. While the C4 I is no longer in production, the 1.6 THP variant remains a popular choice in the used car market. Its combination of performance, fuel efficiency, and modern features makes it an attractive option for buyers seeking a practical and enjoyable compact hatchback. Regular maintenance, including periodic intake valve cleaning, is crucial to ensure the long-term reliability of the 1.6 THP engine. Today, well-maintained examples of the C4 I 1.6 THP 16V can still provide reliable and affordable transportation.



