The BMW 3 Series Sedan (E90) 320i with the Steptronic automatic transmission, produced from 2005 to 2007, represented the entry point into the E90 generation for many American buyers. Positioned below the 323i, 325i, and 328i models, the 320i offered a balance of BMW’s renowned driving dynamics with a more accessible price point and focus on fuel efficiency. It served as a popular choice for those seeking a premium compact sedan without the higher running costs associated with the larger-displacement engines. This variant was primarily sold in markets where smaller displacement engines were favored, and it found a niche among drivers prioritizing comfort and ease of use over outright performance.
Technical Specifications
| Brand | BMW |
| Model | 3 Series |
| Generation | 3 Series Sedan (E90) |
| Type (Engine) | 320i (150 Hp) Steptronic |
| Start of production | 2005 |
| End of production | 2007 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Sedan |
| Seats | 5 |
| Doors | 4 |
| Fuel consumption (urban) | 11 l/100 km (21.4 US mpg) |
| Fuel consumption (extra urban) | 6.2 l/100 km (37.9 US mpg) |
| Fuel consumption (combined) | 7.9 l/100 km (29.8 US mpg) |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 9 sec |
| Acceleration 0 – 62 mph | 9 sec |
| Acceleration 0 – 60 mph | 8.6 sec |
| Maximum speed | 215 km/h (133.59 mph) |
| Weight-to-power ratio | 9.3 kg/Hp |
| Weight-to-torque ratio | 7 kg/Nm |
| Power | 150 Hp @ 6200 rpm |
| Torque | 200 Nm @ 3600 rpm (147.51 lb.-ft. @ 3600 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | N46B20B |
| Engine displacement | 1995 cm3 (121.74 cu. in.) |
| Number of cylinders | 4 |
| Engine configuration | Inline |
| Cylinder Bore | 84 mm (3.31 in.) |
| Piston Stroke | 90 mm (3.54 in.) |
| Compression ratio | 10.5:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Multi-port manifold injection |
| Engine aspiration | Naturally aspirated engine |
| Engine oil capacity | 4.25 l (4.49 US qt | 3.74 UK qt) |
| Coolant capacity | 8 l (8.45 US qt | 7.04 UK qt) |
| Kerb Weight | 1395 kg (3075.45 lbs.) |
| Max. weight | 1840 kg (4056.51 lbs.) |
| Max load | 445 kg (981.06 lbs.) |
| Trunk (boot) space – minimum | 460 l (16.24 cu. ft.) |
| Fuel tank capacity | 60 l (15.85 US gal | 13.2 UK gal) |
| Length | 4520 mm (177.95 in.) |
| Width | 1817 mm (71.54 in.) |
| Height | 1421 mm (55.94 in.) |
| Wheelbase | 2760 mm (108.66 in.) |
| Front track | 1500 mm (59.06 in.) |
| Rear track | 1513 mm (59.57 in.) |
| Drivetrain Architecture | Rear wheel drive |
| Number of gears | 6 |
| Gearbox type | Automatic transmission |
| Front suspension | Spring Strut |
| Rear suspension | Coil spring |
| Front brakes | Ventilated discs |
| Rear brakes | Disc |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Steering rack and pinion |
| Tires size | 205/55 R16 V |
| Wheel rims size | 7J X 16 |
Powertrain & Engine Architecture
The heart of the E90 320i Steptronic is the N46B20B engine, a 2.0-liter inline-four cylinder powerplant. This engine is a naturally aspirated unit featuring double overhead camshafts (DOHC) and four valves per cylinder. It utilizes a multi-port fuel injection system, delivering fuel directly into the intake ports. The N46 engine was known for its relatively smooth operation and decent fuel economy, though it wasn’t without its quirks, including potential issues with the VANOS variable valve timing system and oil leaks. The Steptronic transmission is a 6-speed automatic gearbox, offering smooth shifts and a more relaxed driving experience compared to the available 6-speed manual. This automatic transmission was designed to enhance the car’s usability in everyday traffic conditions.
Driving Characteristics
The 320i Steptronic offered a comfortable and refined driving experience. With 150 horsepower and 147 lb-ft of torque, acceleration was adequate but not particularly brisk. The 0-60 mph time of around 8.6 seconds reflects this. Compared to the more powerful 323i, 325i, and 328i models, the 320i felt noticeably slower, especially during overtaking maneuvers. The automatic transmission, while smooth, could sometimes feel hesitant to downshift, requiring more deliberate throttle input. However, the well-tuned suspension and precise steering maintained BMW’s reputation for engaging handling, providing a confident feel in corners. The gear ratios were optimized for fuel efficiency rather than outright performance.
Equipment & Trim Levels
The 320i typically came standard with features such as automatic climate control, power windows and locks, a CD player, and alloy wheels. Interior upholstery was usually cloth, though leather was available as an option. Common optional extras included a sunroof, upgraded audio system, navigation system, and sport seats. The trim level was generally considered the base model, offering a good level of standard equipment without the luxury features found in the higher-end 3 Series variants. The dashboard layout was typical of the E90 generation, with a driver-focused design and intuitive controls.
Chassis & Braking
The E90 320i utilized a MacPherson strut front suspension and a multi-link rear suspension, providing a good balance of ride comfort and handling precision. The braking system consisted of ventilated discs at the front and solid discs at the rear. Anti-lock brakes (ABS) were standard. The suspension was tuned to provide a comfortable ride, but it also offered good body control during cornering. The weight distribution was relatively balanced, contributing to the car’s predictable handling characteristics. Stabilizer bars were fitted front and rear to reduce body roll.
Market Reception & Comparison
The 320i Steptronic was generally well-received by critics as an affordable and efficient entry point into the BMW 3 Series range. However, some reviewers noted that the engine lacked the punch of the larger-displacement alternatives. Fuel economy was a strong point, with the 320i achieving around 29.8 US mpg in combined driving. Compared to the 323i, the 320i offered lower running costs but sacrificed performance. The 320i was often seen as a sensible choice for those prioritizing practicality and fuel efficiency over driving thrills.
Legacy
The E90 320i with the Steptronic transmission has become a relatively affordable used car option. The N46 engine, while generally reliable, requires regular maintenance to prevent issues with the VANOS system and oil leaks. The Steptronic transmission is also generally durable, but it’s important to ensure it has been serviced according to BMW’s recommendations. Today, these cars are often sought after by enthusiasts looking for an entry-level BMW with a good balance of comfort, handling, and affordability. While not the most powerful or prestigious 3 Series variant, the 320i Steptronic remains a capable and enjoyable compact sedan.
