The BMW Z4 (E85) 3.0si Steptronic, produced from 2006 to 2008, represents the high-performance variant of the first-generation Z4 roadster following the LCI (Life Cycle Impulse) facelift. Positioned as the flagship model, it offered a significant step up in power and refinement compared to the 2.0i and 2.5i versions. The E85 Z4, launched in 2002, aimed to recapture the spirit of the classic BMW roadsters, offering a driver-focused experience in a modern package. The 3.0si Steptronic specifically catered to buyers seeking a blend of performance and convenience, providing the naturally aspirated inline-six engine with a six-speed automatic transmission.
Technical Specifications
| Brand | BMW |
| Model | Z4 |
| Generation | Z4 (E85 LCI, facelift 2006) |
| Type (Engine) | 3.0si (265 Hp) Steptronic |
| Start of production | 2006 |
| End of production | 2008 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Roadster |
| Seats | 2 |
| Doors | 2 |
| Fuel consumption (urban) | 12.8 l/100 km (18.4 US mpg, 22.1 UK mpg, 7.8 km/l) |
| Fuel consumption (extra urban) | 6.8 l/100 km (34.6 US mpg, 41.5 UK mpg, 14.7 km/l) |
| Fuel consumption (combined) | 9 l/100 km (26.1 US mpg, 31.4 UK mpg, 11.1 km/l) |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 6 sec |
| Acceleration 0 – 62 mph | 6 sec |
| Acceleration 0 – 60 mph | 5.7 sec |
| Maximum speed | 250 km/h (155.34 mph) |
| Weight-to-power ratio | 5.3 kg/Hp, 190 Hp/tonne |
| Weight-to-torque ratio | 4.4 kg/Nm, 225.8 Nm/tonne |
| Power | 265 Hp @ 6600 rpm |
| Power per litre | 88.5 Hp/l |
| Torque | 315 Nm @ 2500 rpm (232.33 lb.-ft. @ 2500 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | N52B30A |
| Engine displacement | 2996 cm3 (182.83 cu. in.) |
| Number of cylinders | 6 |
| Engine configuration | Inline |
| Cylinder Bore | 85 mm (3.35 in.) |
| Piston Stroke | 88 mm (3.46 in.) |
| Compression ratio | 10.7:1 |
| 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) |
| Kerb Weight | 1395 kg (3075.45 lbs.) |
| Max. weight | 1650 kg (3637.63 lbs.) |
| Max load | 255 kg (562.18 lbs.) |
| Trunk (boot) space – minimum | 300 l (10.59 cu. ft.) |
| Fuel tank capacity | 55 l (14.53 US gal | 12.1 UK gal) |
| Length | 4091 mm (161.06 in.) |
| Width | 1781 mm (70.12 in.) |
| Height | 1268 mm (49.92 in.) |
| Wheelbase | 2495 mm (98.23 in.) |
| Front track | 1473 mm (57.99 in.) |
| Rear (Back) track | 1523 mm (59.96 in.) |
| Minimum turning circle | 9.8 m (32.15 ft.) |
| Drivetrain Architecture | Rear wheel drive |
| Drive wheel | Rear wheel drive |
| Number of gears and type of gearbox | 6 gears, 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 |
Powertrain & Engine Architecture
The heart of the 3.0si Steptronic is the N52B30A, a 3.0-liter (2996 cc) naturally aspirated inline-six engine. This engine is a descendant of the highly regarded M54 engine, but incorporates several advancements including magnesium alloy construction for the engine block, variable valve timing (VANOS) on both intake and exhaust camshafts, and a more efficient combustion chamber design. The N52 utilizes a multi-port fuel injection system, delivering fuel directly into the intake ports. The engine produces 265 horsepower at 6600 rpm and 315 Nm (232 lb-ft) of torque at 2500 rpm. The six-speed “Steptronic” automatic transmission, a ZF 6HP19, was specifically chosen for its smooth shifting and ability to handle the engine’s power output. It offered both fully automatic operation and a manual shift mode, allowing drivers some control over gear selection.
Driving Characteristics
The 3.0si Steptronic offered a noticeably more engaging driving experience than the lower-powered Z4 variants. While the automatic transmission didn’t provide the same level of driver involvement as the six-speed manual, it offered quick and smooth gear changes. The engine’s strong low-end torque made it responsive in everyday driving situations, while the high-revving nature of the inline-six encouraged spirited driving. Acceleration from 0 to 60 mph took approximately 5.7 seconds, and the car could reach a top speed of 155 mph (limited). Compared to the manual transmission version, the Steptronic traded a slight amount of performance for added convenience. The automatic’s programming prioritized smooth shifts over outright speed, resulting in a slightly slower 0-60 time.
Equipment & Trim Levels
The 3.0si Steptronic came standard with a generous array of features, including leather upholstery, power-adjustable seats, automatic climate control, a premium sound system, and 17-inch alloy wheels. Optional extras included sport seats, navigation system, heated seats, and a wind deflector. The interior design was focused on a driver-centric layout, with all controls within easy reach. The LCI facelift brought subtle interior updates, including revised trim materials and improved switchgear.
Chassis & Braking
The Z4 E85 featured a MacPherson strut front suspension and a multi-link rear suspension, providing a good balance of ride comfort and handling precision. The 3.0si Steptronic benefited from a slightly stiffer suspension setup compared to the base models, further enhancing its handling capabilities. Braking duties were handled by ventilated disc brakes on all four wheels, providing ample stopping power. ABS (Anti-lock Braking System) was standard. The car’s relatively low weight and balanced chassis contributed to its agile handling characteristics.
Market Reception & Comparison
The 3.0si Steptronic was generally well-received by automotive critics. Reviewers praised the engine’s power and smoothness, as well as the car’s engaging handling. The automatic transmission was considered a good compromise for drivers who wanted convenience without sacrificing too much performance. Compared to the 2.5i, the 3.0si offered a significant performance upgrade, while the 2.0i was positioned as a more fuel-efficient entry-level option. The 3.0si’s fuel economy was respectable for a performance roadster, averaging around 26 mpg in combined driving. Reliability was generally good, although some owners reported issues with the VANOS system and oil leaks.
Legacy
The BMW Z4 E85 3.0si Steptronic remains a desirable roadster in the used car market. The N52 engine is known for its durability and relatively low maintenance costs, although regular oil changes and VANOS servicing are crucial. The car’s timeless design and engaging driving experience continue to appeal to enthusiasts. While newer roadsters offer more advanced technology and features, the E85 3.0si Steptronic provides a classic, driver-focused experience that is increasingly rare in modern automobiles. Its combination of performance, refinement, and relative affordability makes it a compelling option for those seeking a fun and engaging open-top sports car.
