Diesel Lives On in Audi’s New SQ5 TDI

Audi reveals a new diesel variant of its second-generation SQ5 ahead of a planned public premiere for the midsize SUV at the 2019 Geneva auto show in early March.

The new SQ5 TDI is planned to go on sale in Europe markets by midyear, but will not be sold in the U.S., Audi says. It debuts a newly developed diesel-electric mild-hybrid drivetrain that uses a number of engineering solutions, including an electric-powered compressor already featured on the German automaker’s larger SQ7.

The new driveline is based on the latest variant of Audi’s turbocharged 3.0L V-6 diesel, which is coupled with a 48V electrical system that forms part of a raft of new mild-hybrid functions. It is used to power a small 7-kW electric motor, which in turn operates the electric compressor.

Mounted downstream of the V-6 diesel's variable-vane exhaust-gas-driven turbocharger, the compressor is designed to boost induction for a reduction in typical turbocharger lag and add low-end performance at engine speeds of up to 1,650 rpm. Alone, it is claimed to be capable of producing up to 20.3 psi (1.4 bar) of pressure, compared to the 34.8 psi (2.4 bar) of conventional exhaust-gas turbochargers.

With 342 hp and 516 lb.-ft. (700 Nm) of torque, the new driveline delivers an additional 7 hp and the same torque loading as the earlier first-generation SQ5 TDI Plus.  By comparison, the existing second-generation turbocharged 3.0L V-6 gasoline-powered SQ5 boasts 349 hp and 369 lb.-ft. (500 Nm) of torque.

Audi quotes a 0-62 mph (100 km/h) time and top speed for the all-wheel-drive SQ5 TDI of 5.1 seconds and 155 mph (250 km/h) respectively.

The mild-hybrid system featured in the new SQ5 TDI includes a belt-driven alternator starter motor connected to the crankshaft. During braking, it is claimed to be capable of recuperating up to 12 kW (16 hp) of kinetic energy, which is stored in a lithium-ion battery mounted within the floor of the rear cargo compartment.

The inclusion of a belt-driven alternator start motor also provides the SQ5 TDI with a coast mode function. It shuts down the engine on short periods of trailing throttle for added fuel savings. Overall consumption is put at 34.6 mpg (6.8 L/100 km) on the correlated European NEDC cycle.

As with its gasoline sibling, the SQ5 TDI receives a standard 8-speed torque-converter-equipped automatic gearbox and all-wheel-drive system. It nominally apportions 40% of drive to the front wheels and 60% to the rear, with the ability to send up to 85% of power to the rear wheels. Buyers can specify the new model with a sports differential for the rear axle, bringing a torque vectoring function to vary the amount of drive channeled to each of the individual rear wheels.

Further options for the new Audi include an adaptive air suspension in place of the standard steel spring setup, which comes with adaptive dampers and a 1.2-in. (30-mm) reduction in ride height over the standard second-generation Q5. There’s also a dynamic steering option with a variable ratio.

The SQ5 TDI is distinguished from standard Q5 models by exterior styling changes including re-profiled bumpers, a brushed-aluminum grille featuring a honeycomb-patterned insert and a rear diffuser. The standard wheels are 20 in. in diameter, with 21-in. items available as an option in combination with red brake calipers.

Inside (above, left), it adopts sports seats upholstered in Alcantara and leather and a leather-bound multifunction steering wheel together with an S-themed 12.3-in. (31-cm) virtual cockpit instrument display and new aluminum trim elements. Among the interior options is a Bang & Olufsen stereo and Audi’s latest connectivity system, which includes wireless smartphone charging.