The Audi A4 B9 8W, specifically the 40 TDI quattro S tronic variant produced from 2018 to 2019, represents a mid-cycle refresh of the fifth generation A4. This model year saw a significant update to the B9 platform, focusing on enhanced technology, improved efficiency, and a more refined driving experience. Positioned as a premium compact executive car, the 40 TDI aimed to balance performance with fuel economy, appealing to buyers seeking a sophisticated and capable all-weather sedan. It occupied a middle ground in the A4 lineup, offering more power and all-wheel drive capability than the entry-level models, but remaining more accessible than the higher-performance S4.
Technical Specifications
| Brand | Audi |
| Model | A4 |
| Generation | A4 (B9 8W, facelift 2018) |
| Type (Engine) | 40 TDI (190 Hp) quattro S tronic |
| Start of production | 2018 |
| End of production | 2019 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Sedan |
| Seats | 5 |
| Doors | 4 |
| Fuel consumption (urban) | 5.8-5.9 l/100 km (40.6 – 39.9 US mpg) |
| Fuel consumption (extra urban) | 4.6-4.8 l/100 km (51.1 – 49 US mpg) |
| Fuel consumption (combined) | 5.0-5.2 l/100 km (47 – 45.2 US mpg) |
| CO2 emissions | 133-138 g/km |
| Fuel Type | Diesel |
| Acceleration 0 – 100 km/h | 7.4 sec |
| Acceleration 0 – 62 mph | 7.4 sec |
| Acceleration 0 – 60 mph | 7 sec |
| Maximum speed | 235 km/h (146.02 mph) |
| Emission standard | Euro 6d – TEMP |
| Weight-to-power ratio | 8.3 kg/Hp |
| Weight-to-torque ratio | 3.9 kg/Nm |
| Power | 190 Hp @ 3800-4200 rpm |
| Torque | 400 Nm @ 1750-3000 rpm (295.02 lb.-ft.) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | DESA, DETA |
| Engine displacement | 1968 cm3 (120.09 cu. in.) |
| Number of cylinders | 4 |
| Engine configuration | Inline |
| Number of valves per cylinder | 4 |
| Fuel injection system | Diesel Commonrail |
| Engine aspiration | Turbocharger, Intercooler |
| Engine oil capacity | 4.7 l (4.97 US qt | 4.14 UK qt) |
| Kerb Weight | 1575 kg (3472.28 lbs.) |
| Trunk (boot) space (minimum) | 480 l (16.95 cu. ft.) |
| Fuel tank capacity | 58 l (15.32 US gal | 12.76 UK gal) |
| Max. roof load | 90 kg (198.42 lbs.) |
| Permitted trailer load with brakes (8%) | 2000 kg (4409.25 lbs.) |
| Permitted trailer load with brakes (12%) | 1800 kg (3968.32 lbs.) |
| Permitted trailer load without brakes | 750 kg (1653.47 lbs.) |
| Permitted towbar download | 80 kg (176.37 lbs.) |
| Length | 4738 mm (186.54 in.) |
| Width | 1842 mm (72.52 in.) |
| Width including mirrors | 2022 mm (79.61 in.) |
| Height | 1428 mm (56.22 in.) |
| Wheelbase | 2820 mm (111.02 in.) |
| Front track | 1572 mm (61.89 in.) |
| Rear track | 1555 mm (61.22 in.) |
| Front overhang | 880 mm (34.65 in.) |
| Rear overhang | 1038 mm (40.87 in.) |
| Drivetrain Architecture | All wheel drive (4×4) |
| Number of gears | 7 |
| Type of gearbox | Automatic transmission S tronic |
| Front suspension | Independent multi-link suspension |
| Rear suspension | Independent multi-link suspension |
| Front brakes | Ventilated discs |
| Rear brakes | Ventilated discs |
INTRODUCTION
The Audi A4 40 TDI quattro S tronic, introduced with the 2018 facelift of the B9 generation, is a four-door, five-seater sedan powered by a 2.0-liter turbocharged diesel engine. This variant was a key offering in Audi’s lineup, designed to appeal to buyers prioritizing fuel efficiency, all-weather capability, and a comfortable driving experience. The facelift brought with it revised styling, updated infotainment systems, and improvements to the engine range, including refinements to the 40 TDI powertrain. The ‘40 TDI’ designation doesn’t directly correlate to engine displacement, but rather represents Audi’s internal power banding system. This model utilizes the VW Group’s modular transverse matrix (MQB) platform, shared with other vehicles like the Volkswagen Passat and Skoda Superb.
Powertrain & Engine Architecture
At the heart of the A4 40 TDI lies the 2.0-liter inline-four cylinder diesel engine, identified by engine codes DESA or DETA depending on specific calibration and market. This engine employs 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 features four valves per cylinder and a variable geometry turbocharger (VGT) to enhance responsiveness across the rev range. The S tronic 7-speed dual-clutch transmission (DCT) is standard, offering quick and smooth gear changes. This transmission is known for its efficiency and responsiveness, contributing to the car’s overall performance and fuel economy. The quattro all-wheel-drive system utilizes a multi-plate clutch to distribute torque between the front and rear axles, providing enhanced traction and stability, particularly in adverse weather conditions.
Driving Characteristics
The 190 horsepower and 400 Nm (295 lb-ft) of torque delivered by the 40 TDI engine provide brisk acceleration, with a 0-60 mph time of around 7 seconds. While not as overtly sporty as higher-performance A4 variants, the 40 TDI offers ample power for everyday driving and highway cruising. The S tronic transmission contributes to a seamless driving experience, with quick shifts and a lack of noticeable torque interruption. The quattro all-wheel-drive system inspires confidence in all conditions, providing excellent grip and stability. Compared to the manual transmission versions, the S tronic offers greater convenience and ease of use, particularly in urban environments. The gear ratios are tuned for a balance of acceleration and fuel efficiency, with taller gearing in higher gears to reduce engine speed at cruising speeds.
Equipment & Trim Levels
The A4 40 TDI quattro S tronic typically came well-equipped as standard. Features included Audi’s MMI infotainment system with a 7-inch display (later upgraded to 10.1-inch touchscreen in some models), automatic climate control, leather upholstery, and a suite of driver-assistance systems such as lane departure warning and automatic emergency braking. Optional extras included a virtual cockpit digital instrument cluster, a premium sound system, adaptive cruise control, and a panoramic sunroof. Trim levels varied by market, but generally offered increasing levels of luxury and technology. Interior upholstery options ranged from standard cloth to premium leather, and dashboard trim could be customized with various wood or aluminum accents.
Chassis & Braking
The A4 B9 utilizes a sophisticated suspension setup, featuring independent multi-link suspension at both the front and rear axles. This provides a comfortable ride quality while maintaining good handling characteristics. The chassis is relatively lightweight, contributing to the car’s agility. Braking duties are handled by ventilated disc brakes on all four wheels, providing ample stopping power. The electronic stability control (ESC) system works in conjunction with the ABS (Anti-lock Braking System) to enhance safety and stability. The 40 TDI variant typically featured a slightly thicker stabilizer bar compared to lower-powered models to reduce body roll during cornering.
Market Reception & Comparison
The Audi A4 40 TDI quattro S tronic was generally well-received by automotive critics. It was praised for its refined engine, comfortable ride, and sophisticated interior. Fuel economy was also a strong point, with the diesel engine delivering impressive MPG figures. Compared to the petrol-powered A4 variants, the 40 TDI offered significantly better fuel efficiency and more torque. Against competitors like the BMW 320d and Mercedes-Benz C220d, the A4 40 TDI was often seen as a strong contender, offering a compelling blend of performance, luxury, and technology. Some criticisms focused on the complexity of the infotainment system and the potential for higher maintenance costs associated with the diesel engine and S tronic transmission.
Legacy
The 2.0-liter TDI engine and S tronic transmission combination used in the A4 40 TDI have proven to be relatively reliable, although regular maintenance is crucial. Like all modern diesel engines, it’s susceptible to issues with the diesel particulate filter (DPF) if not driven on longer journeys periodically. The S tronic transmission requires regular fluid changes to ensure smooth operation. In the used car market, the A4 40 TDI quattro S tronic remains a popular choice, offering a good balance of value, performance, and fuel efficiency. Its all-wheel-drive capability and comfortable ride make it a practical and appealing option for buyers seeking a premium compact executive car.
