In May 2019, CARmag.co.za reported a flagship Mercedes-AMG GT 4-door Coupé, sporting a GT73 badge and 600 kW, could be on the cards. However, German tuner Posaidon has decided to take matters into own hands, handing the current range-topper extra power. 

As standard, the Mercedes-AMG GT63 S’s M177 engine (which we sampled in Texas) produces 470 kW and 900 N.m of torque. The folks at the Mülheim-Kärlich-based company, however, thought the super sedan could use some added power, and equipped it with its R830+ performance package. The tuned twin-turbo 4,0-litre V8 now sends a whopping 647 kW and 1 200 N.m to all four corners via Affalterbach’s clever 4Matic+ all-wheel-drive system.

Thanks to chip-tuning, an uprated turbocharger, a revised intercooler and a new air filter, the firm managed to extract more power from the engine. Further upgrades include tweaks to the exhaust system in the shape of new downpipes.

Coupled with a tweaked nine-speed automatic transmission (to cope with the added oomph), the modified Mercedes-AMG GT63 S now reaches the 100 km/h mark from standstill in a claimed 2,9 seconds (three-tenths quicker than the standard car). Top speed, meanwhile, has been upped from 315 km/h to 350 km/h, with the tuner removing the electronic speed limiter and adjusting the powertrain control unit.