The BMW Z4 G29 30i sDrive Steptronic, produced from 2018 to 2022, represents the third generation of BMW’s iconic two-seater roadster. Positioned as a mid-range offering within the G29 lineup, it aimed to balance performance and affordability, slotting between the entry-level 20i and the higher-performance M40i models. The G29 marked a significant departure from its predecessor, the E89, adopting a more conventional soft-top convertible design and benefiting from a collaborative development effort with Toyota, resulting in the simultaneous launch of the Toyota Supra. This variant was primarily marketed towards enthusiasts seeking a sporty, engaging driving experience with a degree of everyday usability.
Technical Specifications
| Brand | BMW |
| Model | Z4 |
| Generation | Z4 (G29) |
| Type (Engine) | 30i (258 Hp) sDrive Steptronic |
| Start of production | 2018 |
| End of production | 2022 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Roadster |
| Seats | 2 |
| Doors | 2 |
| Fuel consumption (urban) | 7.4 l/100 km (31.8 US mpg) |
| Fuel consumption (extra urban) | 4.9-5.3 l/100 km (48 – 44.4 US mpg) |
| Fuel consumption (combined) | 6.0-6.1 l/100 km (39.2 – 38.6 US mpg) |
| CO2 emissions | 137-139 g/km |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 5.4 sec |
| Acceleration 0 – 62 mph | 5.4 sec |
| Acceleration 0 – 60 mph | 5.1 sec |
| Maximum speed | 250 km/h (155.34 mph) |
| Emission standard | Euro 6 d |
| Weight-to-power ratio | 5.5 kg/Hp |
| Weight-to-torque ratio | 3.5 kg/Nm |
| Power | 258 Hp @ 5000-6500 rpm |
| Torque | 400 Nm @ 1550-4400 rpm (295.02 lb.-ft.) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | B48B20B |
| Engine displacement | 1998 cm3 (121.93 cu. in.) |
| Number of cylinders | 4 |
| Engine configuration | Inline |
| Cylinder Bore | 82 mm (3.23 in.) |
| Piston Stroke | 94.6 mm (3.72 in.) |
| Compression ratio | 10.2:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Direct injection |
| Engine aspiration | Twin-power turbo, Intercooler |
| Engine oil capacity | 5.25 l (5.55 US qt | 4.62 UK qt) |
| Coolant capacity | 8.4 l (8.88 US qt | 7.39 UK qt) |
| Kerb Weight | 1415 kg (3119.54 lbs.) |
| Max. weight | 1740 kg (3836.04 lbs.) |
| Max load | 325 kg (716.5 lbs.) |
| Trunk (boot) space (minimum) | 281 l (9.92 cu. ft.) |
| Fuel tank capacity | 52 l (13.74 US gal | 11.44 UK gal) |
| Length | 4324 mm (170.24 in.) |
| Width | 1864 mm (73.39 in.) |
| Width including mirrors | 2024 mm (79.69 in.) |
| Height | 1304 mm (51.34 in.) |
| Wheelbase | 2470 mm (97.24 in.) |
| Front track | 1609 mm (63.35 in.) |
| Rear track | 1616 mm (63.62 in.) |
| Front overhang | 907 mm (35.71 in.) |
| Rear overhang | 947 mm (37.28 in.) |
| Ride height (ground clearance) | 117 mm (4.61 in.) |
| Drag coefficient (Cd) | 0.29 |
| Minimum turning circle | 11.0 m (36.09 ft.) |
| Drivetrain Architecture | Rear wheel drive |
| Number of gears and type of gearbox | 8 gears, automatic transmission Steptronic |
| Front suspension | Double wishbone |
| 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 | Electric Steering |
| Tires size | 225/50 R17; 255/45 R17 |
| Wheel rims size | 7.5J x 17; 8.5J x 17 |
Powertrain & Engine Architecture
The Z4 30i is powered by BMW’s B48B20B 2.0-liter turbocharged inline-four cylinder engine. This engine is a member of BMW’s modular engine family, known for its efficiency and performance. It utilizes direct fuel injection, a twin-scroll turbocharger, and variable valve timing (Valvetronic) and variable valve lift (Double VANOS) to optimize power delivery and fuel economy. The engine produces 258 horsepower at 5,000-6,500 rpm and 295 lb-ft of torque between 1,550 and 4,400 rpm. The “B48” designation indicates the engine family, while “B20B” specifies the 2.0-liter displacement. The engine is longitudinally mounted, driving the rear wheels. Paired with the engine is BMW’s 8-speed Steptronic automatic transmission. This transmission features a torque converter and offers smooth, quick shifts. It also includes a manual shift mode for more driver involvement.
Driving Characteristics
The Z4 30i sDrive Steptronic delivers a balanced driving experience. While not as aggressively sporty as the M40i, it provides ample power for spirited driving. The 8-speed automatic transmission is well-tuned, offering seamless gear changes and contributing to a refined driving experience. Acceleration from 0 to 60 mph takes approximately 5.1 seconds. The engine’s torque curve is relatively flat, providing good responsiveness across a wide range of engine speeds. Compared to a manual transmission equipped Z4, the automatic offers greater convenience, particularly in urban environments. However, some enthusiasts may find the manual transmission provides a more engaging and connected feel. The rear-wheel drive configuration contributes to a balanced chassis and predictable handling.
Equipment & Trim Levels
The Z4 30i came standard with a generous array of features, including leather upholstery, automatic climate control, a 8.8-inch infotainment system with iDrive controller, and a suite of driver-assistance systems such as lane departure warning and forward collision warning. Optional extras included a premium Harman Kardon sound system, adaptive cruise control, head-up display, and various interior trim options. The standard upholstery was typically a leatherette/cloth combination, with full leather available as an upgrade. Dashboard trim options ranged from aluminum to wood, allowing for some personalization.
Chassis & Braking
The Z4 G29 utilizes a lightweight chassis construction, incorporating high-strength steel and aluminum components. The front suspension features a double-wishbone design, while the rear employs an independent multi-link setup. This configuration provides a good balance of ride comfort and handling precision. The Z4 30i is equipped with ventilated disc brakes on all four wheels, providing ample stopping power. Anti-lock braking system (ABS) is standard, along with electronic stability control (ESC). The suspension tuning is geared towards a sporty yet comfortable ride, offering a good compromise for everyday driving.
Market Reception & Comparison
The Z4 30i was generally well-received by automotive critics. It was praised for its engaging driving dynamics, refined interior, and comfortable ride. However, some reviewers noted that the 2.0-liter engine, while capable, lacked the outright punch of the M40i’s inline-six. Compared to the Z4 20i, the 30i offered a significant performance upgrade, justifying the higher price tag for enthusiasts. Fuel economy was respectable, with combined figures ranging from 38.6 to 39.2 US mpg. Reliability has been generally good, although some owners have reported minor issues with the infotainment system.
Legacy
The BMW Z4 G29 30i sDrive Steptronic has established itself as a desirable used sports car. The B48 engine has proven to be relatively reliable, and the 8-speed automatic transmission is known for its durability. The G29 generation represents a return to form for the Z4, offering a compelling blend of performance, style, and comfort. As the model ages, well-maintained examples are likely to hold their value, appealing to enthusiasts seeking an affordable and engaging roadster experience. The collaborative development with Toyota, resulting in the Supra, has also added to the Z4’s legacy, solidifying its place in automotive history.
