The Citroen C6 I 2.2 HDi Biturbo 16V Automatic, produced between 2007 and 2010, represented a unique offering within the executive sedan segment. Positioned as a mid-range trim within the first generation C6 (2007-2012), this variant combined a powerful biturbo diesel engine with the convenience of an automatic transmission. The C6 itself was Citroen’s ambitious attempt to re-enter the luxury car market, offering a distinctive blend of comfort, technology, and avant-garde styling. This particular engine and transmission pairing aimed to balance performance with fuel efficiency, appealing to drivers seeking a refined and capable grand tourer.
Technical Specifications
| Brand | Citroen |
| Model | C6 |
| Generation | C6 I |
| Type (Engine) | 2.2 HDi Biturbo 16V (170 Hp) Automatic |
| Start of production | 2007 |
| End of production | 2010 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Sedan |
| Seats | 5 |
| Doors | 4 |
| Fuel consumption (urban) | 10.6 l/100 km (22.2 US mpg) |
| Fuel consumption (extra urban) | 5.9 l/100 km (39.9 US mpg) |
| Fuel consumption (combined) | 7.6 l/100 km (30.9 US mpg) |
| CO2 emissions | 199 g/km |
| Fuel Type | Diesel |
| Acceleration 0 – 100 km/h | 11.2 sec |
| Acceleration 0 – 62 mph | 11.2 sec |
| Acceleration 0 – 60 mph | 10.6 sec |
| Maximum speed | 210 km/h (130.49 mph) |
| Emission standard | Euro 4 |
| Weight-to-power ratio | 10.9 kg/Hp |
| Weight-to-torque ratio | 4.6 kg/Nm |
| Power | 170 Hp @ 4000 rpm |
| Torque | 400 Nm @ 1750 rpm (295.02 lb.-ft. @ 1750 rpm) |
| Engine layout | Front, Transverse |
| Engine Model/Code | 4HT DW12BTED4 |
| Engine displacement | 2179 cm3 (132.97 cu. in.) |
| Number of cylinders | 4 |
| Engine configuration | Inline |
| Cylinder Bore | 85 mm (3.35 in.) |
| Piston Stroke | 96 mm (3.78 in.) |
| Compression ratio | 16.6:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Diesel Commonrail |
| Engine aspiration | BiTurbo, Intercooler |
| Valvetrain | DOHC |
| Engine oil capacity | 5.3 l (5.6 US qt | 4.66 UK qt) |
| Coolant | 10.7 l (11.31 US qt | 9.41 UK qt) |
| Kerb Weight | 1848 kg (4074.14 lbs.) |
| Max. weight | 2320 kg (5114.72 lbs.) |
| Max load | 472 kg (1040.58 lbs.) |
| Trunk (boot) space – minimum | 407 l (14.37 cu. ft.) |
| Fuel tank capacity | 72 l (19.02 US gal | 15.84 UK gal) |
| Max. roof load | 80 kg (176.37 lbs.) |
| Permitted trailer load with brakes (8%) | 1700 kg (3747.86 lbs.) |
| Permitted trailer load without brakes | 750 kg (1653.47 lbs.) |
| Permitted towbar download | 70 kg (154.32 lbs.) |
| Length | 4908 mm (193.23 in.) |
| Width | 1860 mm (73.23 in.) |
| Width including mirrors | 2081 mm (81.93 in.) |
| Height | 1464 mm (57.64 in.) |
| Wheelbase | 2900 mm (114.17 in.) |
| Front track | 1586 mm (62.44 in.) |
| Rear (Back) track | 1558 mm (61.34 in.) |
| Front overhang | 1124 mm (44.25 in.) |
| Rear overhang | 884 mm (34.8 in.) |
| Minimum turning circle | 12.43 m (40.78 ft.) |
| Drivetrain Architecture | Front wheel drive |
| Number of gears and type of gearbox | 6 gears, automatic transmission |
| Front suspension | Independent multi-link suspension |
| Rear suspension | Independent multi-link suspension |
| 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 | 225/55 R17; 245/45 R18 |
| Wheel rims size | 17; 18 |
Powertrain & Engine Architecture
The heart of this C6 variant is the 4HT DW12BTED4 engine, a 2.2-liter inline-four diesel. This engine is notable for its biturbo configuration, employing two turbochargers to enhance both low-end torque and high-end power. The use of a common rail direct injection system, delivering fuel at extremely high pressure, optimizes combustion efficiency and reduces emissions. The engine features a double overhead camshaft (DOHC) valvetrain, controlling 16 valves (four per cylinder) for efficient gas exchange. The 16.6:1 compression ratio is typical for a diesel engine, contributing to its thermal efficiency. The automatic transmission is a six-speed unit, designed to provide smooth and responsive gear changes. While the specific transmission model varied, it was generally a conventional torque converter automatic, prioritizing comfort over outright performance.
Driving Characteristics
The 2.2 HDi Biturbo Automatic offered a comfortable and refined driving experience. While not a sports sedan, the 170 horsepower and 400 Nm (295 lb-ft) of torque provided adequate performance for highway cruising and overtaking. The automatic transmission, while smooth, did slightly diminish the engine’s responsiveness compared to the manual versions. The gear ratios were tuned for fuel efficiency and relaxed cruising, rather than aggressive acceleration. Acceleration from 0-60 mph took around 10.6 seconds, and the top speed was 130.49 mph. Compared to the more powerful 2.7 HDi V6, this variant felt noticeably less potent, but it offered a significant improvement in fuel economy.
Equipment & Trim Levels
The 2.2 HDi Biturbo Automatic typically came equipped with a generous level of standard features. These included automatic climate control, power windows and mirrors, a multi-function steering wheel, and a basic audio system. Higher trim levels added features like leather upholstery, premium audio systems, navigation, and parking sensors. The interior design emphasized comfort and spaciousness, with high-quality materials and a focus on ergonomics. Optional extras included a panoramic sunroof, adaptive cruise control, and advanced safety systems.
Chassis & Braking
The C6 I featured an independent multi-link suspension on both the front and rear axles, providing a comfortable ride and good handling characteristics. The suspension was tuned to prioritize ride quality, absorbing bumps and imperfections in the road surface effectively. Braking duties were handled by ventilated discs on all four wheels, providing ample stopping power. An Anti-lock Braking System (ABS) was standard, enhancing safety and stability during emergency braking. The steering was a hydraulic power-assisted rack and pinion system, offering precise and responsive control.
Market Reception & Comparison
The Citroen C6 I 2.2 HDi Biturbo Automatic was generally well-received by critics, who praised its comfortable ride, spacious interior, and fuel efficiency. However, some reviewers noted that the automatic transmission could feel slightly sluggish, and the overall driving experience lacked the sportiness of some competitors. Compared to the 2.7 HDi V6, the 2.2 HDi offered better fuel economy but less performance. Against rivals like the Audi A6, BMW 5 Series, and Mercedes-Benz E-Class, the C6 stood out for its unique styling and focus on comfort, but it often lagged behind in terms of brand prestige and overall refinement.
Legacy
The 4HT DW12BTED4 engine proved to be a relatively reliable unit, although, like any diesel engine, it required regular maintenance and careful servicing. Common issues included turbocharger wear and potential problems with the fuel injection system. The automatic transmission, if properly maintained, also proved to be durable. Today, the C6 I 2.2 HDi Biturbo Automatic represents an interesting and affordable option in the used car market. Its unique styling, comfortable ride, and fuel efficiency continue to appeal to buyers seeking a distinctive and practical executive sedan. However, potential buyers should be aware of the age-related issues common to older vehicles and ensure a thorough inspection before purchase.
