Technical Specifications
| Brand | BMW |
| Model | Z4 |
| Generation | Z4 (E89) |
| Type (Engine) | 23i (204 Hp) sDrive Steptronic |
| Start of production | 2009 |
| End of production | 2011 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Roadster |
| Seats | 2 |
| Doors | 2 |
| Fuel consumption (urban) | 11.8 l/100 km (19.9 US mpg, 23.9 UK mpg, 8.5 km/l) |
| Fuel consumption (extra urban) | 6.1 l/100 km (38.6 US mpg, 46.3 UK mpg, 16.4 km/l) |
| Fuel consumption (combined) | 8.2 l/100 km (28.7 US mpg, 34.4 UK mpg, 12.2 km/l) |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 7.3 sec |
| Acceleration 0 – 62 mph | 7.3 sec |
| Acceleration 0 – 60 mph | 6.9 sec |
| Maximum speed | 239 km/h (148.51 mph) |
| Emission standard | Euro 5 |
| Weight-to-power ratio | 7.4 kg/Hp, 135.5 Hp/tonne |
| Weight-to-torque ratio | 6 kg/Nm, 166.1 Nm/tonne |
| Power | 204 Hp @ 6400 rpm |
| Power per litre | 81.7 Hp/l |
| Torque | 250 Nm @ 2750 rpm (184.39 lb.-ft. @ 2750 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | N52B25A |
| Engine displacement | 2497 cm3 (152.38 cu. in.) |
| Number of cylinders | 6 |
| Engine configuration | Inline |
| Cylinder Bore | 82 mm (3.23 in.) |
| Piston Stroke | 78.8 mm (3.1 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 | 6.5 l (6.87 US qt | 5.72 UK qt) |
| Coolant | 8.5 l (8.98 US qt | 7.48 UK qt) |
| Kerb Weight | 1505 kg (3317.96 lbs.) |
| Max. weight | 1760 kg (3880.14 lbs.) |
| Max load | 255 kg (562.18 lbs.) |
| Trunk (boot) space – minimum | 180 l (6.36 cu. ft.) |
| Trunk (boot) space – maximum | 310 l (10.95 cu. ft.) |
| Fuel tank capacity | 55 l (14.53 US gal | 12.1 UK gal) |
| Length | 4239 mm (166.89 in.) |
| Width | 1790 mm (70.47 in.) |
| Height | 1291 mm (50.83 in.) |
| Wheelbase | 2496 mm (98.27 in.) |
| Front track | 1511 mm (59.49 in.) |
| Rear (Back) track | 1537 mm (60.51 in.) |
| Minimum turning circle | 9.8 m (32.15 ft.) |
| Drivetrain Architecture | Rear wheel drive |
| Number of gears | 6 |
| Gearbox type | Automatic transmission |
| Front suspension | Spring Strut |
| Rear suspension | Coil spring |
| Front brakes | Ventilated discs |
| Rear brakes | Ventilated discs |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Steering rack and pinion |
| Power steering | Electric Steering |
| Tires size | 225/45 R17 |
| Wheel rims size | 8J x 17 |
The BMW Z4 (E89) 23i sDrive Steptronic, produced from 2009 to 2011, represented a key entry point into the second generation of BMW’s popular roadster. Positioned within the E89 Z4 lineup, which spanned a range of engine options, the 23i offered a balance between performance and affordability. It served as a more accessible alternative to the higher-performance 35i and 35is models, targeting buyers who prioritized a comfortable driving experience and stylish design over outright speed. The E89 generation marked a significant departure from its predecessor (E85), adopting a retractable hardtop roof – a feature aimed at improving practicality and refinement.
Powertrain & Engine Architecture
The heart of the Z4 23i is BMW’s N52B25A inline-six engine. This 2.5-liter naturally aspirated engine is a descendant of BMW’s long-respected M52 and M54 families, known for their smooth power delivery and reliability. The N52 introduced several advancements, including a magnesium alloy engine block, double VANOS variable valve timing (for both intake and exhaust camshafts), and a plastic intake manifold. These features contributed to improved efficiency and responsiveness. Fuel is delivered via multi-port fuel injection, and the engine produces 204 horsepower at 6400 rpm and 250 Nm (184 lb-ft) of torque at 2750 rpm. The engine is longitudinally mounted, driving the rear wheels. Paired with the N52B25A is a six-speed Steptronic automatic transmission. This transmission offered both fully automatic operation and the ability for the driver to manually select gears, providing a degree of control without the full commitment of a manual gearbox.
Driving Characteristics
The Z4 23i sDrive Steptronic offered a comfortable and refined driving experience. While not as overtly sporty as the 35i models, the 23i provided ample power for everyday driving and enjoyable weekend excursions. The automatic transmission, while smooth, did slightly diminish the sense of connection to the engine compared to the available six-speed manual. Gear ratios were tuned for a balance of acceleration and fuel economy. The 0-60 mph time of around 6.9 seconds was respectable for the era, but noticeably slower than the manual transmission equipped version. The engine’s torque curve provided good mid-range punch, making it easy to overtake and merge onto highways. However, the engine did require higher revs to deliver its peak power, and the automatic transmission sometimes hesitated during quick downshifts.
Equipment & Trim Levels
The Z4 23i typically came standard with features such as leatherette upholstery, automatic climate control, a multi-function steering wheel, and a basic audio system. Optional extras included leather upholstery, heated seats, a premium sound system, navigation, and parking sensors. The interior design was driver-focused, with a relatively simple and functional layout. Trim levels were not extensively differentiated in the 23i; options were largely selected à la carte. The retractable hardtop was a significant feature, providing coupe-like security and weather protection when raised, and open-air enjoyment when lowered.
Chassis & Braking
The Z4 E89 utilized a MacPherson strut front suspension and a multi-link rear suspension, providing a good balance of ride comfort and handling precision. The chassis was relatively lightweight, contributing to the car’s agility. Braking duties were handled by ventilated disc brakes on all four wheels, providing adequate stopping power. Anti-lock braking system (ABS) was standard. The 23i typically featured slightly smaller tires (225/45 R17) compared to the higher-performance models, prioritizing comfort over ultimate grip.
Market Reception & Comparison
The Z4 23i was generally well-received by automotive critics as an accessible and enjoyable roadster. It was praised for its stylish design, comfortable ride, and refined engine. However, some reviewers noted that the automatic transmission could feel somewhat sluggish, and that the engine lacked the outright punch of the 35i models. Compared to the Z4 35i, the 23i offered significantly better fuel economy, but at the cost of performance. The 23i also represented a more affordable entry point into Z4 ownership, making it attractive to a wider range of buyers. Reliability was generally good, although preventative maintenance, particularly regarding oil leaks common to the N52 engine, was important.
Legacy
The Z4 E89 23i sDrive Steptronic remains a popular choice in the used car market. The N52 engine is known for its durability, although regular maintenance is crucial to prevent oil leaks and ensure long-term reliability. The retractable hardtop continues to be a desirable feature. While not the fastest or most technologically advanced roadster available, the Z4 23i offers a compelling combination of style, comfort, and driving enjoyment, making it a well-rounded and appealing option for those seeking an affordable and reliable open-top experience.
