Audi A8 (2014) is 664 kg (1,464 lbs) lighter than Rolls-Royce Phantom (2017).
Rolls-Royce Phantom (2017) is 705 mm (27.76 inch) longer, 42 mm (1.65 inch) wider, 178 mm (7.01 inch) higher and has 79 liters (2.79 ft3) bigger cargo space than Audi A8 (2014).