2021 is going out with a proverbial bang for G-Power as the German tuner decided to save the best for last. Based on what is already the most powerful production BMW ever – until the XM arrives – the aftermarket specialist has now tinkered with the M5 CS. It has managed to extract an immense output from the twin-turbo V8 few people would expect to find in a midsize sedan.

The 4.4-liter pushes out a massive 627 horsepower and 553 pound-feet (750 Newton-meters) of torque in stock configuration, but obviously, that wasn’t enough to satisfy G-Power’s unquenchable thirst for power. Its stage 1 program starts off “sensibly” with a bump in output to 700 hp and 625 lb-ft (850 Nm) courtesy strictly of a software update. Once you add the custom exhaust system part of the GP-740 package, you’re looking at 740 hp and 664 lb-ft (900 Nm).

Stepping up to the tuner’s GP-780 kit adds upgraded downpipes to unlock a meaty 780 hp and 700 lb-ft (950 Nm) from the ubiquitous S63 engine. The cars featured in the official gallery have the GP-820 kit with all the previously mentioned mods, plus beefier turbochargers and 100-mm quad exhaust tips in carbon or forged carbon. As the name of the package suggests, the V8 is tuned to 820 hp and a mountain-moving 738 lb-ft (1,000 Nm).

The meanest packages of the bunch come along with forged pistons and connecting rods. The G5M Hurricane RS ups the power ante to 840 hp and 775 lb-ft (1,050 Nm), while the G5M Hurricane RR unleashes a colossal 900 hp while retaining the same amount of torque. G-Power installs an electronic top speed limiter preventing the M5 CS from exceeding 207 mph (333 km/h).

There’s no word about acceleration performance, but you can rest assured BMW’s super sedan now needs less than the 2.9 seconds it takes the standard M5 CS to hit 60 mph (three seconds until 62 mph) from a standstill. Aside from the extra oomph, G-Power has 20- and 21-inch custom forged wheels to choose from for the one-year-only flagship sedan.

[Source: G-Power]