Technical Specifications
| Brand | BMW |
| Model | Z4 |
| Generation | Z4 (G29) |
| Type (Engine) | M40i (382 Hp) Steptronic |
| Start of production | September, 2018 |
| End of production | 2022 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Roadster |
| Seats | 2 |
| Doors | 2 |
| Fuel consumption (economy) – urban (EPA) | 9.8 l/100 km (24 US mpg, 28.8 UK mpg, 10.2 km/l) |
| Fuel consumption (economy) – extra urban (EPA) | 7.6 l/100 km (30.9 US mpg, 37.2 UK mpg, 13.2 km/l) |
| Fuel consumption (economy) – combined (EPA) | 9 l/100 km (26.1 US mpg, 31.4 UK mpg, 11.1 km/l) |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 60 mph | 3.9 sec |
| Maximum speed | 250 km/h (155.34 mph), Electronically limited |
| Emission standard | LEV III |
| Weight-to-power ratio | 4.1 kg/Hp, 244.6 Hp/tonne |
| Weight-to-torque ratio | 3.1 kg/Nm, 320.1 Nm/tonne |
| Power | 382 Hp @ 5000-6500 rpm |
| Power per litre | 127.4 Hp/l |
| Torque | 500 Nm @ 1600-4500 rpm (368.78 lb.-ft. @ 1600-4500 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | B58B30O1 |
| Engine displacement | 2998 cm3 (182.95 cu. in.) |
| Number of cylinders | 6 |
| Engine configuration | Inline |
| Cylinder Bore | 82 mm (3.23 in.) |
| Piston Stroke | 94.6 mm (3.72 in.) |
| Compression ratio | 11:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Direct injection |
| Engine aspiration | Twin-power turbo, Intercooler |
| Valvetrain | VALVETRONIC, Double-VANOS |
| Engine oil capacity | 6.5 l (6.87 US qt | 5.72 UK qt) |
| Kerb Weight | 1562 kg (3443.62 lbs.) |
| Max. weight | 1856 kg (4091.78 lbs.) |
| Max load | 294 kg (648.16 lbs.) |
| Trunk (boot) space – minimum | 280 l (9.89 cu. ft.) |
| Fuel tank capacity | 52 l (13.74 US gal | 11.44 UK gal) |
| Length | 4336 mm (170.71 in.) |
| Width | 1864 mm (73.39 in.) |
| Width including mirrors | 2024 mm (79.69 in.) |
| Height | 1306 mm (51.42 in.) |
| Wheelbase | 2470 mm (97.24 in.) |
| Front track | 1595 mm (62.8 in.) |
| Rear (Back) track | 1590 mm (62.6 in.) |
| Front overhang | 919 mm (36.18 in.) |
| Rear overhang | 947 mm (37.28 in.) |
| Ride height (ground clearance) | 120 mm (4.72 in.) |
| Drag coefficient (Cd) | 0.29-0.35 |
| Minimum turning circle (turning diameter) | 11 m (36.09 ft.) |
| Drivetrain Architecture | The Internal combustion engine (ICE) drives the rear wheels of the vehicle. |
| Drive wheel | Rear wheel drive |
| Number of gears and type of gearbox | 8 gears, automatic transmission Steptronic |
| Front suspension | Spring Strut, Transverse stabilizer |
| Rear suspension | Independent multi-link spring suspension with stabilizer |
| 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 | Front wheel tires: 255/40 R18; 255/35 R19 Rear wheel tires: 275/40 R18; 275/35 R19 |
| Wheel rims size | Front wheel rims: 9J x 18; 9J x 19 Rear wheel rims: 10J x 18; 10J x 19 |
The G29 generation BMW Z4, launched in 2018, marked a significant departure from its predecessor, the E89. Developed in collaboration with Toyota (resulting in the simultaneous creation of the Toyota Supra), the G29 Z4 returned to a traditional roadster layout with a front-engine, rear-wheel-drive configuration. The M40i variant, introduced alongside the base sDrive30i, served as the performance leader, offering a substantial increase in power and a more engaging driving experience. Production continued until 2022, with the M40i remaining a consistent top-seller within the Z4 range.
Powertrain & Engine Architecture
At the heart of the Z4 M40i lies the BMW B58B30O1 3.0-liter inline-six engine. This engine is a member of BMW’s modular engine family and features a single twin-scroll turbocharger, direct fuel injection, and BMW’s VALVETRONIC variable valve timing and Double-VANOS variable camshaft timing systems. These technologies work in concert to deliver a broad torque curve and responsive performance. The engine produces 382 horsepower at 5,000-6,500 rpm and 368.78 lb-ft of torque between 1,600 and 4,500 rpm. The engine’s longitudinal mounting and rear-wheel-drive configuration contribute to its balanced handling characteristics.
Power is transmitted to the rear wheels through an eight-speed Steptronic automatic transmission. This transmission offers smooth and quick shifts, and includes paddle shifters for manual control. The transmission is tuned for both performance and efficiency, with optimized gear ratios to maximize acceleration and fuel economy. The automatic transmission was chosen to broaden the appeal of the M40i, offering ease of use alongside its performance capabilities.
Driving Characteristics
The Z4 M40i delivers a thrilling driving experience characterized by its responsive engine, precise steering, and well-controlled chassis. The 3.9-second 0-60 mph acceleration time is indicative of its performance potential. The automatic transmission provides seamless gear changes, although some enthusiasts may prefer the more engaging experience of a manual gearbox (which was not offered in the M40i). The suspension is tuned to provide a balance between comfort and handling, offering a firm but not overly harsh ride. The electronic limited-slip differential enhances traction and stability during cornering.
Compared to the Z4 sDrive30i, the M40i offers a noticeably more powerful and engaging driving experience. The increased torque of the inline-six engine provides stronger acceleration in all gears, while the upgraded suspension and brakes contribute to improved handling and stopping power. While the sDrive30i prioritizes fuel efficiency and comfort, the M40i is geared towards drivers who prioritize performance and driving enjoyment.
Equipment & Trim Levels
The Z4 M40i came standard with a comprehensive list of features, including leather upholstery, power-adjustable seats with memory function, a premium sound system, and a navigation system. Standard exterior features included 19-inch alloy wheels, an M Sport aerodynamic package, and adaptive LED headlights. Optional extras included a head-up display, a driver assistance package (including adaptive cruise control and lane departure warning), and a variety of interior trim options. The interior design emphasized a driver-focused layout with a modern and minimalist aesthetic.
Chassis & Braking
The Z4 M40i features a lightweight chassis constructed from high-strength steel and aluminum. The suspension consists of a spring-strut front axle and a multi-link rear axle, both with stabilizer bars. The M40i benefits from stiffer springs and dampers compared to the sDrive30i, resulting in reduced body roll and improved handling. The braking system consists of ventilated discs on all four wheels, providing ample stopping power. The M Sport brakes, available as an option, offered even greater stopping performance.
Market Reception & Comparison
The Z4 M40i was generally well-received by automotive critics, who praised its powerful engine, engaging handling, and stylish design. Some reviewers noted that the ride could be firm on rough roads, and that the lack of a manual transmission was a drawback for some enthusiasts. However, the overall consensus was that the M40i was a compelling sports car that offered a strong alternative to its competitors. Compared to the Porsche 718 Boxster, the Z4 M40i offered a more comfortable ride and a lower price point, while the Boxster was often praised for its more precise handling and overall refinement.
Legacy
The Z4 G29 M40i represents a modern interpretation of the classic BMW roadster formula. Its potent inline-six engine and engaging driving dynamics have cemented its place as a desirable sports car. While long-term reliability data is still emerging, the B58 engine has proven to be generally robust and reliable. On the used car market, the Z4 M40i commands a premium over the base sDrive30i, reflecting its higher performance and desirability. The G29 Z4, and particularly the M40i variant, is expected to remain a sought-after model for enthusiasts for years to come.
