4 Minutes
G-Power Lowers the Roof on the BMW M4 Convertible
G-Power has turned its attention from the M3 Sedan to the open-top BMW M4 Convertible, producing the bold G4M Bi-Turbo conversion. Visually restrained yet aggressive, this convertible sits on new wheels and presents a stealthy, rocket-like stance with the sky visible above—but it’s what’s under the skin that really matters for tuners and performance enthusiasts.
Design and Styling Upgrades
Exterior enhancements
The G4M Bi-Turbo receives a reworked hood and a series of front bumper attachments that sharpen the M4’s presence. G-Power lists additional aerodynamic items on its website, including a front splitter, a redesigned kidney grille, and a rear wing to increase downforce and visual impact. These parts are pitched to harmonize with the convertible’s lines while improving airflow and stance.
Interior options
On the inside, the tuner offers upgrades such as new steering wheels, paddle shifters, premium floor mats, and full reupholstery for those who want a bespoke cabin. Customers can tailor both aesthetics and tactile quality if budget allows.
Performance and Technical Specifications
According to G-Power, the headline upgrade for the G4M Bi-Turbo is a 700 metric horsepower spec—listed as 690 bhp (515 kW) with 627 lb-ft (850 Nm) of torque. That level of output places the tuned M4 in the company of earlier supercars and side-by-side with G-Power’s recent M3 project, which was reported to have a top speed around 193 mph (310 kph).
G-Power’s catalog shows a range of power stages, so owners can choose the level that fits their needs and budget: 592 hp (600 PS / 441 kW), 611 hp (620 PS / 456 kW), 641 hp (650 PS / 478 kW), 661 hp (670 PS / 493 kW) and a punchiest 720 PS (approx. 710 bhp). Pricing in Germany for these upgrades is listed at €3,685 for the entry 600 PS tune, €14,900 for the 700 PS package, and €35,700 for the top 720 PS upgrade.
Market Positioning and Value
G-Power’s top-tier upgrade is expensive—almost the price of a new compact coupe—so it’s clearly aimed at buyers who prioritize maximum performance and exclusivity over cost. For many M3/M4 owners, mid-level tunes will offer a more practical balance between expense and performance gains.
How It Stacks Up: Comparisons
Compared with the factory BMW M4 Competition xDrive Convertible, which produces around 523 bhp (530 PS / 390 kW) and sprints to 60 mph in about 3.6 seconds, the G-Power conversions significantly increase straight-line capability and torque. The tuner’s creations can approach or surpass the performance of some previous-generation supercars in a drag or high-speed run, though real-world acceleration figures for each tune vary and depend on traction, cooling, and drivetrain setup.
Practical considerations
Potential buyers should weigh tuning costs, warranty implications and everyday drivability. High-output conversions often require supporting upgrades to cooling, suspension and brakes to ensure reliability and safety at elevated speeds.
Summary
The G-Power G4M Bi-Turbo transforms the BMW M4 Convertible into a striking, high-performance open-top machine. With multiple tuning stages up to roughly 720 PS and a suite of visual and interior options, the package targets enthusiasts who want exotic-level straight-line performance while retaining the convertible experience. For those seeking factory-backed convenience, the M4 Competition xDrive Convertible remains a compelling alternative with supercar-like acceleration straight from BMW.
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