BMW never made an M4 Gran Coupe, but G-Power is ready to fix that. The German aftermarket specialist has worked on the B58 engine that goes inside the M440i. Even though it’s still one of many not-quite-M cars, the M Performance model’s tremendous tuning potential means it can outpunch a stock S58 with a few mods.
In standard guise, the turbocharged 3.0-liter engine delivers 369 hp and 500 Nm (369 lb-ft) in the M440i. However, G-Power worked its magic to elevate those numbers. The upgraded inline-six now pumps out 513 hp and 700 Nm (516 lb-ft), making it stronger than the rear-wheel-drive M4s. It’s only down by 10 hp compared to the M4 xDrive, which now makes 523 hp for the 2025 model year.
The added oomph was obtained following a turbocharger upgrade, a custom exhaust, and a new charge air cooler. G-Power also applied some software wizardry to maximize performance and reach M4 levels of output. There are three lesser tuning kits available, but if you want to go all out, the GP-520 package is the one to get.
G-Power has already modified a bunch of cars aside from the G26 4 Series Gran Coupe. The G22 Coupe and G23 Cabriolet have received the extra power as well. In addition, these M440i models get 20-inch forged wheels in different designs, combined with 235/35 front and 275/30 rear tires. Go for the two-door coupe and there’s a rear wing, too.
Reach deeper into your pocket and the interior can be customized with a carbon fiber treatment for the steering wheel and shift paddles. Elsewhere, you can have velour floor mats while the seats can be reupholstered in a different leather.
Because the B58 goes into other M Performance models, G-Power will happily work on your M340i or M240i. The six-cylinder unit is also found in non-BMWs, including the Toyota Supra, Ineos Grenadier, and Morgan Plus Six.
Source: G-Power
