The BMW Z4 G29 M40i, produced from 2018 to 2022, represents the high-performance variant of the third-generation Z4 Roadster. Positioned as the flagship model within the G29 lineup, it aimed to deliver a compelling blend of sporting dynamics and open-top driving pleasure. The G29 Z4 marked a significant departure from its predecessor, the E89, adopting a more conventional roadster silhouette and benefiting from a collaborative development effort with Toyota, resulting in the simultaneous creation of the Toyota Supra. The M40i trim specifically targeted enthusiasts seeking a substantial power upgrade over the base 2.0-liter models, offering a sophisticated and engaging driving experience.
Technical Specifications
| Brand | BMW |
| Model | Z4 |
| Generation | Z4 (G29) |
| Type (Engine) | M40i (340 Hp) Steptronic |
| Start of production | 2018 |
| End of production | 2022 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Roadster |
| Seats | 2 |
| Doors | 2 |
| Fuel consumption (urban) | 9.2 l/100 km (25.6 US mpg) |
| Fuel consumption (extra urban) | 5.9-6.3 l/100 km (39.9 – 37.3 US mpg) |
| Fuel consumption (combined) | 7.1-7.4 l/100 km (33.1 – 31.8 US mpg) |
| CO2 emissions | 162-168 g/km |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 4.5 sec |
| Acceleration 0 – 62 mph | 4.5 sec |
| Acceleration 0 – 60 mph | 4.3 sec |
| Maximum speed | 250 km/h (155.34 mph) |
| Emission standard | Euro 6 d |
| Weight-to-power ratio | 4.5 kg/Hp |
| Weight-to-torque ratio | 3.1 kg/Nm |
| Power | 340 Hp @ 5000-6500 rpm |
| Torque | 500 Nm @ 1600-4500 rpm (368.78 lb.-ft.) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | B58B30C |
| 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 |
| Engine oil capacity | 6.5 l (6.87 US qt | 5.72 UK qt) |
| Coolant | 10.5 l (11.1 US qt | 9.24 UK qt) |
| Kerb Weight | 1535 kg (3384.1 lbs.) |
| Max. weight | 1860 kg (4100.6 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 | 1594 mm (62.76 in.) |
| Rear (Back) track | 1589 mm (62.56 in.) |
| Front overhang | 907 mm (35.71 in.) |
| Rear overhang | 947 mm (37.28 in.) |
| Ride height (ground clearance) | 114 mm (4.49 in.) |
| Drag coefficient (Cd) | 0.31 |
| Minimum turning circle | 11.0 m (36.09 ft.) |
| Drive wheel | All wheel drive (4×4) |
| 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 |
Powertrain & Engine Architecture
The heart of the Z4 M40i is BMW’s B58B30C 3.0-liter inline-six engine. This engine is a member of the modular B-series engine family, known for its robust construction and high output. The B58 utilizes a single, twin-scroll turbocharger with an integrated exhaust manifold, contributing to rapid response and minimal turbo lag. Direct fuel injection, combined with Valvetronic variable valve timing and Double VANOS variable camshaft timing, optimizes combustion efficiency and power delivery. The engine produces 340 horsepower at 5,000-6,500 rpm and 368 lb-ft of torque between 1,600 and 4,500 rpm. This power is channeled through an eight-speed Steptronic automatic transmission, which features optimized shift programming for both spirited driving and fuel efficiency. The transmission offers both automatic and manual shift modes, with paddle shifters available for driver control.
Driving Characteristics
The Z4 M40i delivers a distinctly sporty driving experience. The combination of the potent inline-six engine and the responsive eight-speed automatic results in brisk acceleration – 0 to 60 mph in approximately 4.3 seconds. The automatic transmission’s gear ratios are well-matched to the engine’s torque curve, providing strong pull in any gear. Compared to the base 2.0-liter Z4 models, the M40i offers a significantly more engaging and rewarding driving experience, with noticeably quicker response and greater overall performance. While the automatic transmission is generally smooth and efficient, some drivers may prefer the greater control offered by a manual gearbox, which was not available in the M40i configuration.
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 aerodynamic body kit, and adaptive LED headlights. Optional extras included a head-up display, a wind deflector, and various interior trim options. The M40i also benefited from a sport-tuned suspension and upgraded brakes compared to the lower trims.
Chassis & Braking
The Z4 M40i features a lightweight chassis construction, utilizing high-strength steel and aluminum components to minimize weight and maximize rigidity. The suspension consists of a double-wishbone front suspension and a multi-link rear suspension, providing precise handling and a comfortable ride. The braking system features ventilated discs at all four corners, providing ample stopping power. The M40i also incorporates BMW’s Dynamic Stability Control (DSC) system, which helps to maintain stability and control in challenging driving conditions.
Market Reception & Comparison
The Z4 M40i was generally well-received by automotive critics, who praised its powerful engine, engaging handling, and refined interior. It was often compared favorably to its rivals, such as the Porsche 718 Boxster and the Audi TT RS. While the Z4 M40i offered a compelling performance package, some critics noted that its fuel economy was not class-leading. However, the M40i’s overall balance of performance, comfort, and features made it a popular choice among enthusiasts.
Legacy
The BMW Z4 G29 M40i represents a modern interpretation of the classic roadster formula. Its potent engine, sophisticated chassis, and refined interior have ensured its continued appeal in the used car market. The B58 engine, in particular, has earned a reputation for reliability and durability, making the M40i a desirable option for buyers seeking a high-performance roadster with long-term ownership potential. As a final iteration of the G29 platform, the M40i stands as a testament to BMW’s commitment to delivering a thrilling and engaging driving experience.
