The Audi A4 40 TDI quattro ultra Mild Hybrid S tronic, produced from September 2020 to 2024, represents a significant iteration of the B9 (8W) generation A4, following the 2019 facelift. This variant occupied a key position in Audi’s lineup, offering a blend of performance, efficiency, and all-weather capability aimed at buyers seeking a premium compact executive sedan. It leverages a 2.0-liter turbocharged diesel engine paired with a mild hybrid system and Audi’s renowned quattro all-wheel-drive, packaged with a seven-speed S tronic dual-clutch transmission. The “40 TDI” designation reflects Audi’s power-based naming scheme, indicating a power output roughly equivalent to 400 PS (metric horsepower), though the actual output is 204 horsepower.
Technical Specifications
| Brand | Audi |
| Model | A4 |
| Generation | A4 (B9 8W, facelift 2019) |
| Type (Engine) | 40 TDI (204 Hp) quattro ultra 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) | 5.1-5.8 l/100 km (46.1 – 40.6 US mpg) |
| CO2 emissions (WLTP) | 133-152 g/km |
| Fuel consumption (urban) | 5.4-5.6 l/100 km (43.6 – 42 US mpg) |
| Fuel consumption (extra urban) | 3.9-4.3 l/100 km (60.3 – 54.7 US mpg) |
| Fuel consumption (combined) | 4.5-4.8 l/100 km (52.3 – 49 US mpg) |
| CO2 emissions (NEDC) | 118-126 g/km |
| Fuel Type | Diesel |
| Acceleration 0 – 100 km/h | 6.9 sec |
| Acceleration 0 – 62 mph | 6.9 sec |
| Acceleration 0 – 60 mph | 6.6 sec |
| Maximum speed | 210 km/h (130.49 mph) |
| Emission standard | Euro 6d-ISC-FCM |
| Weight-to-power ratio | 7.8 kg/Hp |
| Weight-to-torque ratio | 4 kg/Nm |
| Power | 204 Hp @ 3800-4200 rpm |
| Torque | 400 Nm @ 1750-3250 rpm (295.02 lb.-ft.) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | DTPA |
| 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 | 15.5:1 |
| 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 | 11.9 l (12.57 US qt | 10.47 UK qt) |
| Kerb Weight | 1590 kg (3505.35 lbs.) |
| Max. weight | 2160 kg (4761.98 lbs.) |
| Max load | 570 kg (1256.63 lbs.) |
| Trunk (boot) space (minimum) | 460 l (16.24 cu. ft.) |
| Fuel tank capacity | 58 l (15.32 US gal | 12.76 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%) | 2000 kg (4409.25 lbs.) |
| Permitted trailer load (brakes 12%) | 1800 kg (3968.32 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.) |
| Drag coefficient (Cd) | 0.25 |
| Minimum turning circle | 11.6 m (38.06 ft.) |
| Drivetrain Architecture | ICE and electric motor drive front wheels, rear drive via clutch |
| Drive wheel | All wheel drive (4×4) |
| 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 |
INTRODUCTION
The Audi A4 40 TDI quattro ultra Mild Hybrid S tronic, launched in late 2020, is a key variant within the facelifted B9 A4 range. Building upon the already successful B9 platform (introduced in 2015), this model benefits from updated styling, enhanced technology, and a refined powertrain. The “ultra” designation signifies Audi’s efficiency-focused all-wheel-drive system, which prioritizes front-wheel drive for fuel economy and engages the rear axle only when needed. This variant aimed to provide a balance between performance, fuel efficiency, and all-weather capability, appealing to a broad range of buyers in the premium compact executive segment. It was primarily sold in the European market, where diesel engines and all-wheel drive remain popular choices.
Powertrain & Engine Architecture
At the heart of the A4 40 TDI lies the DTPA engine, a 2.0-liter inline-four cylinder diesel engine. This engine utilizes a common rail direct injection system, delivering fuel at extremely high pressures for optimized combustion. A single turbocharger with an intercooler provides forced induction, boosting power and torque. The engine boasts a high compression ratio of 15.5:1, contributing to its efficiency. The mild hybrid system, a 48-volt system, incorporates a belt starter generator (BSG) that recovers energy during deceleration and assists the engine during acceleration, improving fuel economy and reducing emissions. The seven-speed S tronic dual-clutch transmission offers quick and smooth gear changes, enhancing both performance and driving comfort. This transmission is known for its efficiency and responsiveness, contributing to the overall driving experience.
Driving Characteristics
The 40 TDI quattro ultra delivers a refined and capable driving experience. With 204 horsepower and 400 Nm (295 lb-ft) of torque, it provides ample power for everyday driving and confident overtaking. The S tronic transmission ensures brisk acceleration, with a 0-60 mph time of around 6.6 seconds. The quattro all-wheel-drive system provides excellent traction in various conditions, enhancing stability and control. Compared to the more powerful TDI variants (like the 45 TDI), the 40 TDI offers a slightly less aggressive driving experience, prioritizing fuel efficiency and comfort. The gear ratios are tuned for a balance between acceleration and fuel economy, with taller gears for relaxed cruising on the highway. The mild hybrid system is largely imperceptible during normal driving, seamlessly assisting the engine when needed.
Equipment & Trim Levels
The A4 40 TDI quattro ultra typically came well-equipped, reflecting its premium positioning. Standard features often included Audi’s Virtual Cockpit digital instrument cluster, a touchscreen infotainment system with Apple CarPlay and Android Auto compatibility, automatic climate control, and a suite of driver-assistance systems such as lane departure warning and automatic emergency braking. Interior upholstery was typically a combination of cloth and leatherette, with optional upgrades to full leather available. Trim levels varied by market, but generally offered options for upgraded wheels, exterior styling packages, and enhanced interior features like heated seats and a premium sound system.
Chassis & Braking
The A4 40 TDI utilizes an independent multi-link suspension setup at both the front and rear axles, providing a comfortable and controlled ride. The suspension is tuned to balance handling and comfort, offering a good compromise for everyday driving. Braking duties are handled by ventilated discs at the front and solid discs at the rear. The car is equipped with ABS (Anti-lock Braking System), electronic stability control, and other advanced braking aids. The “ultra” quattro system employs a multi-plate clutch to engage the rear axle when needed, optimizing fuel efficiency by primarily driving the front wheels.
Market Reception & Comparison
The Audi A4 40 TDI quattro ultra Mild Hybrid S tronic was generally well-received by automotive critics. It was praised for its refined engine, comfortable ride, and efficient all-wheel-drive system. Compared to the higher-output TDI variants, the 40 TDI offered a more affordable entry point into the A4 range, while still providing a satisfying driving experience. Fuel economy was a key strength, with real-world figures often exceeding the official WLTP ratings. Reliability has been generally good, although, like all modern diesel engines, it’s susceptible to issues with the diesel particulate filter (DPF) if not driven on longer journeys periodically.
Legacy
The A4 40 TDI quattro ultra Mild Hybrid S tronic represents a significant step in Audi’s ongoing efforts to improve fuel efficiency and reduce emissions. The combination of a refined diesel engine, mild hybrid technology, and the quattro all-wheel-drive system proved to be a popular formula. On the used car market, these models are generally sought after for their blend of practicality, performance, and fuel economy. The DTPA engine has proven to be relatively robust, although regular maintenance is crucial to ensure long-term reliability. As with any used vehicle, a thorough inspection is recommended before purchase, paying particular attention to the condition of the DPF and the S tronic transmission.
