The Audi Q8 sport concept at the Geneva Motor Show features a 3.0 TFSI V6 engine with a 48-volt electrical system and mild hybrid technology, providing eight-cylinder performance with the consumption of a four-cylinder.
This is the first time that advanced Electrically Powered Compressor (EPC) technology first used by Audi in the SQ7 TDI appears in a TFSI petrol engine.
The latest Q8 study combines its EPC with a six-cylinder TFSI and a mild hybrid system – a world first that enables it to deliver 476PS output with the efficiency of a four-cylinder equivalent.
Augmented by the compressor and Mhev system, the 3.0 TFSI engine powers the Q8 sport concept from 0-62mph in just 4.7 seconds and on to a top speed of 170mph. It also has a range of more than 745 miles.
Thanks to the recuperation performance of 20 kW, the Q8 sport concept has a considerable fuel economy advantage over a model equipped with a regular TFSI six-cylinder engine without the mHEV system, with a 25g/km lower CO2 output.
The 450PS 3.0 TFSI six-cylinder engine is combined with an electric powered compressor and a mild hybrid system for recuperation. The starter generator positioned between the crankshaft and the transmission handles recuperation and, if required, can work in the opposite direction as an additional electric motor. The 48-volt electrical system assures the supply of electrical power.
The energy recovered as part of recuperation can, if required, be used to increase performance. During boost operation – where the combustion engine and electric motor are used simultaneously – the electric motor’s additional 20 kW of output and its torque of 170 Nm (125.4 lb-ft) open up a total of 350 kW of power to the engine and bring its total torque up to 700 Nm (516.3 lb-ft).
Positioned at the rear under the luggage compartment, the lithium-ion battery with an energy storage capacity of 0.9 kWh makes it possible to keep moving slowly in stop-start traffic with the combustion engine switched off, as well as allowing for manoeuvres and parking under electric power alone. During braking, efficient recuperation using the 20-kW-strong starter generator quickly recharges the battery to ensure that the vehicle can regularly be driven under electric power.
In addition to the two exhaust gas turbochargers, the electric powered compressor provides the Q8 sport concept with an additional kick by supplying the three-litre six-cylinder engine with fresh air. The electric powered compressor supports the turbochargers at times when the exhaust gas is insufficient for rapid development of power. It therefore opens up delay-free acceleration to the V6 petrol engine – something previously only known to diesel engines and electric motors.
The electric powered compressor is positioned in a bypass downstream of the intercooler, i.e. close to the engine. Instead of the turbine wheel, it integrates a compact electric motor. It accelerates the engine’s compressor wheel up to 70,000 rpm in less than 250 milliseconds. With the support of the electric powered compressor, the power of the 3.0 TFSI is always rapidly available as soon as the accelerator is depressed, even at low engine speeds.
The Q8 sport concept drive system with its V6 TFSI and additional electric motor supplies the performance of a true eight-cylinder engine, yet with the fuel consumption of a frugal four-cylinder. That’s because, compared with a similar engine without mild hybrid system, the consumption reduces by more than a litre per 100 kilometres, despite serving up 20 kW of additional power. The total range of the Q8 sport concept equipped with an 85-litre fuel tank is more than 745 miles.
When driving, the drive system management controls the operating states of the Audi: the SUV can boost, coast and recuperate as appropriate for the situation. The predictive efficiency assistant is a standard feature which supports the driver by supplying detailed information on the vehicle surroundings to the control unit. Route data from the navigation system and Car-to-X services from Audi connect are also taken into account.
The Audi Q8 sport concept features quattro permanent all-wheel drive. Adaptive air suspension sport – an air suspension system with controlled damping – sets the ground clearance in five levels with 90mm height differences.