The BMW Z4 (G29) 20i sDrive Steptronic, produced from 2018 to 2022, represents the entry point into the third generation of BMW’s iconic roadster. Positioned within the G29 chassis code, which marked a significant departure from its predecessor with a co-development partnership with Toyota (resulting in the Toyota GR86/Subaru BRZ), the 20i offered a blend of sporty handling and accessible performance. This variant aimed to attract buyers seeking the Z4 experience without the higher price tag and increased performance of the more powerful trims like the 30i or the M40i. It served as a crucial volume seller in markets where fuel efficiency and lower running costs were prioritized, particularly in Europe and Asia, while still offering a premium driving experience expected of the BMW brand.
Technical Specifications
| Brand | BMW |
| Model | Z4 |
| Generation | Z4 (G29) |
| Type (Engine) | 20i (197 Hp) sDrive Steptronic |
| Start of production | 2018 |
| End of production | 2022 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Roadster |
| Seats | 2 |
| Doors | 2 |
| Combined fuel consumption (WLTP) | 7.1-7.2 l/100 km (33.1 – 32.7 US mpg, 39.8 – 39.2 UK mpg, 14.1 – 13.9 km/l) |
| CO2 emissions (WLTP) | 160-165 g/km |
| Fuel consumption (economy) – urban (NEDC) | 7.2 l/100 km (32.7 US mpg, 39.2 UK mpg, 13.9 km/l) |
| Fuel consumption (economy) – extra urban (NEDC) | 5.2 l/100 km (45.2 US mpg, 54.3 UK mpg, 19.2 km/l) |
| Fuel consumption (economy) – combined (NEDC) | 6 l/100 km (39.2 US mpg, 47.1 UK mpg, 16.7 km/l) |
| CO2 emissions (NEDC) | 136 g/km |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 6.6 sec |
| Acceleration 0 – 62 mph | 6.6 sec |
| Acceleration 0 – 60 mph | 6.3 sec |
| Maximum speed | 240 km/h (149.13 mph) |
| Emission standard | Euro 6d |
| Weight-to-power ratio | 7.3 kg/Hp, 137.8 Hp/tonne |
| Weight-to-torque ratio | 4.5 kg/Nm, 223.8 Nm/tonne |
| Power | 197 Hp @ 4500-6500 rpm |
| Power per litre | 98.6 Hp/l |
| Torque | 320 Nm @ 1450-4200 rpm (236.02 lb.-ft. @ 1450-4200 rpm) |
| 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 |
| Valvetrain | VALVETRONIC, Double-VANOS |
| Engine oil capacity | 5.25 l (5.55 US qt | 4.62 UK qt) |
| Coolant | 8.4 l (8.88 US qt | 7.39 UK qt) |
| Kerb Weight | 1430 kg (3152.61 lbs.) |
| Max. weight | 1740 kg (3836.04 lbs.) |
| Max load | 310 kg (683.43 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 (Back) 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 (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: 225/50 R17; 225/45 R18; 255/35 R19Rear wheel tires: 255/45 R17; 255/40 R18; 275/35 R19 |
| Wheel rims size | Front wheel rims: 7.5J x 17; 8J x 18; 9J x 19Rear wheel rims: 8.5J x 17; 9J x 18; 10J x 19 |
INTRODUCTION
The BMW Z4 (G29) 20i sDrive Steptronic, launched in 2018, marked a return to the classic roadster formula for BMW. This generation Z4 moved away from the retractable hardtop of the E89, opting for a traditional soft top, and benefited from a new platform co-developed with Toyota. The 20i variant, powered by a 2.0-liter turbocharged four-cylinder engine, served as the entry-level model, offering a balance between performance, fuel economy, and affordability. It was designed to appeal to a broader audience than previous Z4 iterations, attracting buyers who desired a stylish and engaging sports car for everyday use.
Powertrain & Engine Architecture
At the heart of the Z4 20i lies the BMW B48B20B engine, a 2.0-liter inline-four cylinder gasoline engine. This engine utilizes direct fuel injection and is equipped with a twin-scroll turbocharger, along with BMW’s VALVETRONIC variable valve timing and Double-VANOS variable camshaft timing systems. These technologies contribute to both increased power output and improved fuel efficiency. The engine produces 197 horsepower at 4500-6500 rpm and 320 Nm (236 lb-ft) of torque between 1450-4200 rpm. The engine is longitudinally mounted, driving the rear wheels. Paired with the B48 engine is BMW’s 8-speed Steptronic automatic transmission. This transmission offers smooth and quick shifts, and includes features like launch control and shift paddles for a more engaging driving experience. The transmission’s gear ratios are tuned for a balance of acceleration and fuel economy, with a relatively tall final drive to enhance cruising efficiency.
Driving Characteristics
The Z4 20i sDrive Steptronic delivers a comfortable and engaging driving experience. While not as overtly sporty as the higher-powered Z4 variants, the 20i provides ample power for spirited driving on winding roads. The 8-speed automatic transmission contributes to smooth acceleration, and the engine’s broad torque curve ensures responsive performance in most situations. Compared to a manual transmission equipped Z4, the Steptronic offers convenience and ease of use, particularly in urban environments. However, some enthusiasts may find the automatic transmission slightly less engaging than a manual. The rear-wheel drive configuration provides a balanced chassis and predictable handling, while the relatively lightweight construction of the G29 platform contributes to agile cornering.
Equipment & Trim Levels
The Z4 20i sDrive Steptronic came standard with a comprehensive list of features, including BMW’s iDrive infotainment system with a 8.8-inch touchscreen display, automatic climate control, leather upholstery, and a suite of safety features such as automatic emergency braking and lane departure warning. Optional extras included features like a head-up display, premium sound system, adaptive cruise control, and various interior trim options. Trim levels were relatively streamlined, with most customization occurring through individual options rather than distinct packages. Interior upholstery options typically included various leather colors and finishes, while exterior colors offered a range of metallic and non-metallic paints.
Chassis & Braking
The Z4 20i utilizes a MacPherson strut front suspension and a multi-link rear suspension, both incorporating stabilizer bars to minimize body roll. The suspension is tuned for a balance of comfort and handling, providing a compliant ride on most road surfaces. Braking duties are handled by ventilated disc brakes on all four wheels, providing ample stopping power. The standard braking system is equipped with ABS (Anti-lock Braking System) and electronic brake-force distribution. The car’s weight distribution is close to 50/50, contributing to balanced handling characteristics.
Market Reception & Comparison
The Z4 20i was generally well-received by automotive critics, who praised its stylish design, comfortable ride, and engaging handling. However, some reviewers noted that the 2.0-liter engine, while capable, lacked the outright performance of the larger engines offered in the Z4 lineup. Compared to the Z4 30i, the 20i offered a more affordable entry point but sacrificed some performance. The 20i also provided better fuel economy than the 30i and M40i models. In terms of reliability, the B48 engine has proven to be generally robust, although some owners have reported issues with the cooling system and oil leaks.
Legacy
The BMW Z4 (G29) 20i sDrive Steptronic represents a compelling option in the used sports car market. Its combination of style, comfort, and affordability makes it an attractive choice for buyers seeking a premium roadster experience. The B48 engine is known for its reliability and relatively low maintenance costs, making the 20i a practical choice for everyday use. As the G29 Z4 continues to age, the 20i variant is likely to remain a popular choice for those who prioritize value and fuel efficiency without sacrificing the driving enjoyment that BMW is known for.
