The Audi A4 (B9 8W) 30 TDI Mild Hybrid S tronic, produced from September 2020 to 2024, represents a key offering within the facelifted B9 generation of Audi’s popular compact executive sedan. Positioned as a fuel-efficient and technologically advanced option, this variant aimed to balance performance with economy, appealing to buyers seeking a refined driving experience with lower running costs. It falls within the broader A4 lineup, which included more powerful petrol and diesel engines, as well as sportier S4 models. The “30 TDI” designation signifies its engine output and diesel fuel type, while “Mild Hybrid” and “S tronic” denote its hybrid assistance and dual-clutch transmission, respectively.
Technical Specifications
| Brand | Audi |
| Model | A4 |
| Generation | A4 (B9 8W, facelift 2019) |
| Type (Engine) | 30 TDI (136 Hp) Mild Hybrid S tronic |
| Start of production | September, 2020 |
| End of production | 2024 |
| Powertrain Architecture | MHEV (Mild Hybrid Electric Vehicle) |
| Body type | Sedan |
| Seats | 5 |
| Doors | 4 |
| Combined fuel consumption (WLTP) | 4.5-5.4 l/100 km (52.3 – 43.6 US mpg) |
| CO2 emissions (WLTP) | 119-141 g/km |
| Fuel consumption (urban) | 5.0-5.2 l/100 km (47 – 45.2 US mpg) |
| Fuel consumption (extra urban) | 3.5-3.8 l/100 km (67.2 – 61.9 US mpg) |
| Fuel consumption (combined) | 4.0-4.3 l/100 km (58.8 – 54.7 US mpg) |
| CO2 emissions (NEDC) | 106-114 g/km |
| Fuel Type | Diesel |
| Acceleration 0 – 100 km/h | 9.5 sec |
| Acceleration 0 – 62 mph | 9.5 sec |
| Acceleration 0 – 60 mph | 9 sec |
| Maximum speed | 210 km/h (130.49 mph) |
| Emission standard | Euro 6d-ISC-FCM |
| Weight-to-power ratio | 10.8 kg/Hp |
| Weight-to-torque ratio | 4.6 kg/Nm |
| Power | 136 Hp @ 3000-4200 rpm |
| Torque | 320 Nm @ 1500-2750 rpm (236.02 lb.-ft.) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | DEZB |
| Engine displacement | 1968 cm3 (120.09 cu. in.) |
| Number of cylinders | 4 |
| Engine configuration | Inline |
| Cylinder Bore | 81 mm (3.19 in.) |
| Piston Stroke | 95.5 mm (3.76 in.) |
| Compression ratio | 16:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Diesel Commonrail |
| Engine aspiration | Turbocharger, Intercooler |
| Engine oil capacity | 5.5 l (5.81 US qt | 4.84 UK qt) |
| Coolant capacity | 11.2 l (11.83 US qt | 9.85 UK qt) |
| Kerb Weight | 1475 kg (3251.82 lbs.) |
| Max. weight | 2090 kg (4607.66 lbs.) |
| Max load | 615 kg (1355.84 lbs.) |
| Trunk (boot) space (minimum) | 460 l (16.24 cu. ft.) |
| Fuel tank capacity | 40 l (10.57 US gal | 8.8 UK gal) |
| AdBlue tank capacity | 12 l (3.17 US gal | 2.64 UK gal) |
| Max. roof load | 90 kg (198.42 lbs.) |
| Permitted trailer load (brakes 8%) | 1700 kg (3747.86 lbs.) |
| Permitted trailer load (brakes 12%) | 1500 kg (3306.93 lbs.) |
| Permitted trailer load (no brakes) | 750 kg (1653.47 lbs.) |
| Permitted towbar download | 80 kg (176.37 lbs.) |
| Length | 4762 mm (187.48 in.) |
| Width | 1847 mm (72.72 in.) |
| Width including mirrors | 2022 mm (79.61 in.) |
| Height | 1431 mm (56.34 in.) |
| Wheelbase | 2820 mm (111.02 in.) |
| Front track | 1572 mm (61.89 in.) |
| Rear track | 1555 mm (61.22 in.) |
| Front overhang | 899 mm (35.39 in.) |
| Rear overhang | 1043 mm (41.06 in.) |
| Drag coefficient (Cd) | 0.25 |
| Minimum turning circle | 11.6 m (38.06 ft.) |
| Drivetrain Architecture | ICE and electric motor drive front wheels (MHEV) |
| Drive wheel | Front wheel drive |
| Number of gears | 7 |
| Gearbox type | Automatic transmission S tronic |
| Front suspension | Independent multi-link |
| Rear suspension | Independent multi-link |
| Front brakes | Ventilated discs |
| Rear brakes | Disc |
Powertrain & Engine Architecture
The heart of the A4 30 TDI is the 2.0-liter inline-four cylinder diesel engine, specifically the DEZB engine code. This engine utilizes a turbocharger with an intercooler to boost power and efficiency. It employs a common rail direct fuel injection system, delivering fuel directly into the combustion chamber at extremely high pressure for optimized combustion. The engine boasts 136 horsepower at 3000-4200 rpm and 320 Nm (236 lb-ft) of torque between 1500-2750 rpm. Crucially, this variant incorporates a 48-volt mild hybrid system. This system features a belt starter generator (BSG) and a small lithium-ion battery. The BSG allows for extended start-stop functionality, regenerative braking to recoup energy, and a slight power boost during acceleration. The engine is paired with Audi’s seven-speed S tronic dual-clutch transmission, known for its quick and smooth gear changes. This transmission contributes to both performance and fuel efficiency.
Driving Characteristics
The 136 hp output and S tronic transmission provide a comfortable and efficient driving experience. Acceleration from 0-100 km/h (0-62 mph) takes 9.5 seconds, which is adequate for everyday driving but doesn’t offer particularly sporty performance. The S tronic transmission is well-programmed, offering seamless shifts and responsive performance. Compared to the more powerful 40 TDI variants, the 30 TDI feels less urgent in acceleration, particularly when overtaking. However, the readily available torque from the diesel engine provides good in-gear acceleration. The mild hybrid system is largely imperceptible during normal driving, contributing to a refined and quiet cabin experience. The gear ratios are tuned for fuel economy, meaning the engine doesn’t rev as high as in sportier models.
Equipment & Trim Levels
The A4 30 TDI Mild Hybrid S tronic typically came well-equipped, reflecting Audi’s premium positioning. Standard features generally included Audi’s MMI infotainment system with a touchscreen display, automatic climate control, LED headlights, and a suite of driver-assistance systems such as lane departure warning and forward collision warning. Interior upholstery was typically cloth or a combination of cloth and leatherette. Optional extras included a virtual cockpit digital instrument cluster, a premium sound system, leather upholstery, and a panoramic sunroof. Trim levels varied by market, but generally offered progressive upgrades in terms of interior materials, exterior styling, and technology features.
Chassis & Braking
The A4 B9 utilizes a sophisticated chassis design featuring independent multi-link suspension at both the front and rear. This setup provides a comfortable ride quality while maintaining good handling characteristics. The 30 TDI variant, being a lower-powered model, typically featured slightly smaller brakes compared to the higher-performance versions. Front brakes were ventilated discs, while rear brakes were solid discs. The steering system is an electric power steering system, offering precise and responsive control. Stabilizer bars are fitted to both axles to reduce body roll during cornering.
Market Reception & Comparison
The A4 30 TDI Mild Hybrid S tronic was generally well-received by automotive critics for its fuel efficiency and refined driving experience. It was praised for its comfortable ride, quiet cabin, and advanced technology. Compared to the more powerful A4 diesel variants, the 30 TDI offered a more affordable entry point into the A4 range, appealing to buyers prioritizing economy over outright performance. Fuel economy figures of 4.5-5.4 l/100 km (52.3-43.6 US mpg) were competitive within its segment. Reliability reports suggest that the DEZB engine and S tronic transmission are generally reliable, although regular maintenance is crucial.
Legacy
The Audi A4 B9 30 TDI Mild Hybrid S tronic represents a significant step in Audi’s push towards greater fuel efficiency and electrification. The mild hybrid technology, while not a full hybrid system, demonstrated Audi’s commitment to reducing emissions and improving fuel economy. On the used car market, these models are generally sought after for their balance of practicality, refinement, and running costs. The DEZB engine, when properly maintained, has proven to be a durable and reliable unit. As with any used vehicle, a thorough inspection and service history check are recommended before purchase.
