How does the Audi A7 Sportback fare against the multi-door luxury coupe Porsche Panamera and the Mercedes CLS?

Audi A7 Sportback 3.0 TDI
Price: from $135,750
Engine: 3.0-litre V6 turbodiesel; 180kW/580Nm
Transmission: 8-speed auto, AWD
Thirst: 5.9L/100km; 156g/km CO2

Porsche Panamera S
Price: from $287,100
Engine: 4.8-litre V8 petrol; 294kW/500Nm
Transmission: 7-speed dual-clutch auto, RWD
Thirst: 10.5L/100km; 247g/km CO2

Mercedes-Benz CLS 350 CDI
Price: from $159,200
Engine: 3.0-litre V6 turbodiesel; 195kW/620Nm
Transmission: 7-speed auto, RWD
Thirst: 6.2L/100km; 163g/km CO2