With most of the test mule’s camouflage removed, it’s clear to see just how extensively the model’s styling has been lifted from the four-door GT 63.
Large air dams reside up front while chunky, twin-tip mufflers rest on either side of a rear diffuser.
However, Mercedes has kept the covers on the GT 73’s rear bumper and – most importantly – its charging port.
The GT 73 is expected to use the same 4.0-litre turbocharged V8 engine found in the GT 63, although the new flagship model will have its engine mated to a hybrid system.
This should push outputs “up to 600kw” and bring the 0-100km/h time to less than three seconds. By way of comparison, the GT 63 outputs 470kW and sees 100km/h from a standstill in 3.2 seconds.
The Mercedes-AMG GT 73 is set to compete with Porsche’s performance hybrid four-door offering, the Panamera Turbo S E-Hybrid Sport Turismo.
Mercedes-AMG has previously teased a 2020 debut for the model.