Technical Specifications
| Brand | Opel |
| Model | Astra |
| Generation | Astra H TwinTop |
| Type (Engine) | 1.8i 16V ECOTEC (140 Hp) |
| Start of production | May, 2006 |
| End of production | June, 2010 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Coupe – Cabriolet |
| Seats | 4 |
| Doors | 2 |
| Fuel consumption (urban) | 10.3 l/100 km (22.8 US mpg, 27.4 UK mpg, 9.7 km/l) |
| Fuel consumption (extra urban) | 6.2 l/100 km (37.9 US mpg, 45.6 UK mpg, 16.1 km/l) |
| Fuel consumption (combined) | 7.7 l/100 km (30.5 US mpg, 36.7 UK mpg, 13 km/l) |
| CO2 emissions | 185 g/km |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 11.4 sec |
| Acceleration 0 – 62 mph | 11.4 sec |
| Acceleration 0 – 60 mph | 10.8 sec |
| Maximum speed | 209 km/h (129.87 mph) |
| Emission standard | Euro 4 |
| Weight-to-power ratio | 10 kg/Hp, 100 Hp/tonne |
| Weight-to-torque ratio | 8 kg/Nm, 125 Nm/tonne |
| Power | 140 Hp @ 6300 rpm |
| Power per litre | 78 Hp/l |
| Torque | 175 Nm @ 3800 rpm (129.07 lb.-ft. @ 3800 rpm) |
| Engine layout | Front, Transverse |
| Engine Model/Code | Z18XER |
| Engine displacement | 1796 cm3 (109.6 cu. in.) |
| Number of cylinders | 4 |
| Engine configuration | Inline |
| Cylinder Bore | 80.5 mm (3.17 in.) |
| Piston Stroke | 88.2 mm (3.47 in.) |
| Compression ratio | 10.5:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Multi-port manifold injection |
| Engine aspiration | Naturally aspirated engine |
| Valvetrain | DOHC |
| Engine oil capacity | 4.25 l (4.49 US qt | 3.74 UK qt) |
| Coolant | 6.1 l (6.45 US qt | 5.37 UK qt) |
| Kerb Weight | 1400 kg (3086.47 lbs.) |
| Max. weight | 1870 kg (4122.64 lbs.) |
| Max load | 470 kg (1036.17 lbs.) |
| Trunk (boot) space – minimum | 205 l (7.24 cu. ft.) |
| Trunk (boot) space – maximum | 440 l (15.54 cu. ft.) |
| Fuel tank capacity | 52 l (13.74 US gal | 11.44 UK gal) |
| Length | 4476 mm (176.22 in.) |
| Width | 1759 mm (69.25 in.) |
| Width with mirrors folded | 1831 mm (72.09 in.) |
| Width including mirrors | 2021 mm (79.57 in.) |
| Height | 1411 mm (55.55 in.) |
| Wheelbase | 2614 mm (102.91 in.) |
| Front track | 1488 mm (58.58 in.) |
| Rear (Back) track | 1481 mm (58.31 in.) |
| Front overhang | 909 mm (35.79 in.) |
| Rear overhang | 953 mm (37.52 in.) |
| Ride height (ground clearance) | 122 mm (4.8 in.) |
| Drag coefficient (Cd) | 0.31 |
| Minimum turning circle | 11.2 m (36.75 ft.) |
| Drivetrain Architecture | The Internal combustion engine (ICE) drives the front wheels of the vehicle. |
| Drive wheel | Front wheel drive |
| Number of gears and type of gearbox | 5 gears, manual transmission |
| Front suspension | Coil spring |
| Rear suspension | Transverse stabilizer |
| Front brakes | Ventilated discs |
| Rear brakes | Disc |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Steering rack and pinion |
| Tires size | 205/55 R16 |
| Wheel rims size | 16 |
The Opel Astra H TwinTop 1.8i 16V ECOTEC, produced from May 2006 to June 2010, was a popular choice for drivers seeking an affordable and stylish convertible. Positioned as a mid-range offering within the TwinTop lineup, it provided a more accessible entry point compared to the higher-performance OPC variants. Built on the Astra H platform (A04), this model aimed to balance fuel efficiency with enjoyable driving dynamics in a two-door coupe-convertible package. A key feature of the TwinTop was its fully automatic retractable hardtop, a significant improvement over the fabric roofs found on earlier Astra convertibles.
Powertrain & Engine Architecture
The Astra H TwinTop 1.8i is powered by the Z18XER engine, a 1.8-liter (1796 cc) inline-four cylinder engine. This engine is part of Opel’s Ecotec family, which emphasizes efficiency and refinement. The Z18XER utilizes multi-port fuel injection and a double overhead camshaft (DOHC) valvetrain with four valves per cylinder, resulting in 140 horsepower at 6300 rpm and 175 Nm (129 lb-ft) of torque at 3800 rpm. The engine has a compression ratio of 10.5:1. While a five-speed manual transmission was standard, a four-speed automatic transmission was also available. The automatic, while convenient, generally resulted in slower acceleration and slightly reduced fuel economy compared to the manual version.
Driving Characteristics
The 1.8i TwinTop offered a comfortable and refined driving experience. With 140 hp, acceleration was adequate for daily driving, reaching 0-60 mph in around 10.8 seconds. However, it wasn’t designed for high performance. The automatic transmission, while smooth, could feel somewhat hesitant during overtaking. The car’s weight, approximately 1400 kg (3086 lbs), contributed to a less agile feel than lighter Astra models. The suspension, tuned for comfort, provided a reasonably smooth ride, but didn’t offer the sporty handling of the OPC. Power delivery was linear and predictable.
Equipment & Trim Levels
The 1.8i TwinTop typically included air conditioning, electric front windows, central locking, and a CD stereo system as standard equipment. Higher trim levels offered options such as leather upholstery, heated seats, alloy wheels, and upgraded audio systems. Safety features included ABS brakes, front airbags, and side airbags. The retractable hardtop was a defining feature, providing coupe-like security and weather protection when closed, and open-air enjoyment when lowered. Interior trim levels varied, with base models featuring cloth upholstery and simpler dashboard finishes, while higher trims offered more premium materials.
Chassis & Braking
The Astra H TwinTop featured a MacPherson strut front suspension and a torsion beam rear suspension. Ventilated discs were used for the front brakes, providing good stopping power, while solid discs were used in the rear. ABS (Anti-lock Braking System) was standard. The chassis was reinforced to compensate for the structural rigidity lost with the removal of the fixed roof. Stabilizer bars were fitted to both axles to minimize body roll during cornering. The standard tire size was 205/55 R16, offering a balance of grip and ride comfort.
Market Reception & Comparison
The Astra H TwinTop 1.8i was generally well-received as a stylish and practical convertible. Some reviewers noted that the performance wasn’t particularly exciting, and the automatic transmission could feel somewhat dated. Compared to the more powerful OPC version, the 1.8i offered a more affordable entry point, but at the cost of performance. Fuel economy was reasonable, achieving around 30.5 US mpg on the combined cycle. Reliability was generally good, although some owners reported minor issues with the retractable hardtop mechanism.
Legacy
The Opel Astra H TwinTop 1.8i remains a popular choice in the used car market for those seeking an affordable and stylish convertible. The Z18XER engine is known for its durability, and with proper maintenance, it can provide many years of reliable service. Potential buyers should be aware of potential issues with the retractable hardtop mechanism and have it thoroughly inspected before purchase. The TwinTop represents a significant advancement in Opel’s convertible offerings, combining practicality, style, and open-air driving enjoyment.
