This Tuned BMW Convertible Is About to Embarrass So Many Supercars

German tuner G-Power has turned the M4 convertible into a 700-hp droptop missile.

Front view of a matte black sports car with a distinctive kidney grille, carbon fiber hood vents, sleek LED headlights, and bronze-colored alloy wheels. The license plate reads "G-POWER.

Published August 27, 2025

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From the factory, BMW M cars are hardly lacking in horsepower — even on the low end, output comes in around 500 ponies.

Of course, in the case of tuners like Germany’s G-Power, even those numbers aren’t enough to get the job done. There’s still more potential for power.

Black convertible sports car with a distinctive large front grille, sleek headlights, and bronze-colored alloy wheels, parked in front of a modern industrial building. The car has a "G-POWER" license plate. — G-Power’s G4M Bi-Turbo convertible makes for a stealthy convertible with its matte paint.

Just take the outfit’s G4M Bi-Turbo convertible build, for example. Clad in carbon fiber and tuned to the limit, it’s capable of being a true supercar slayer — and for a fraction of the price.

Drag-ready droptop

With power coming from a turbocharged 3.0-liter inline-six, even the base BMW M4 is rated for a healthy 473 horses.

However, following an ECU unlock, some GP performance software, a new carbon intake system and an upgraded stainless steel Deeptone exhaust setup, G-Power claims that the M4-based droptop you see before you is now putting down as much as 700 ponies.

Matte black convertible sports car with copper-colored alloy wheels, parked in front of a modern black building with two large garage doors. The car's roof is down, showcasing its sleek, aerodynamic design. — The five-spoke Hurricane RR wheels offer a nice contrast against the black paint and exposed carbon fiber.

Though the tuner doesn’t openly specify what this means from an acceleration or a top speed standpoint, the G4M has to be quick.

For one, G-Power’s less powerful GP-620 package is supposedly good for a 192-mph top speed. What’s more, a G3M running the GP-700 software is rated for a top speed of 205 mph.

Matte black convertible sports car with the top down, featuring sleek aerodynamic lines, copper-colored alloy wheels, and modern LED tail lights. The interior is black with a digital dashboard and two front seats visible. The car is parked on a paved surface next to a tiled area with a drainage grate. The rear license plate reads "G-POWER. — The interior is a refreshingly subtle affair, without too much branding to detract from the look.

In any case, 200-mph convertibles are typically Ferraris or McLarens that would cost you a quarter of a million dollars or more — not a BMW with some fancy tuning wizardry.

An exercise in restraint

While G-Power’s G4M convertible touts supercar-level power, the droptop is considerably more understated in its appearance.

Even with a Venturi carbon fiber hood, a set of Shuriken carbon fiber panels and a modified grille, it’s a subtle build. It’s not quite a sleeper, but the matte paint and exposed weave provide a nice contrast against the Hurricane forged wheels.

Close-up of a matte gray car hood featuring two carbon fiber vented sections and a circular emblem with the letter "G" and the word "Grotta" on it. The vents have a textured, layered design and reflect light subtly. — The Venturi hood is easily the flashiest aspect of G-Power’s G4M Bi-Turbo convertible build.

Moreover, there’s refreshingly little branding compared to most names in the aftermarket tuning space. On that note, the interior is clean and simple.

Now, assuming you’d like to step things up a notch, G-Power does offer add-ons like a carbon fiber wing, various paint configurations, alternate wheel options and more.

Black convertible sports car with aggressive front design, featuring a prominent hood scoop and two vented sections on the hood. The car has sleek, angular headlights and a large front grille with a "G-POWER" badge. The interior shows four seats with headrests, and the car is parked on a paved surface. — A convertible offers engaging open-air thrills — especially when top speed is north of 200 mph.

Pricing and availability

If you’re looking to have the experts over at G-Power modify your car, the brand currently provides services for AMG, BMW, Lamborghini and Porsche.

In the case of the M4, G-Power offers à la carte upgrades as well as complete tuning packages.

Black convertible sports car with a matte finish, featuring distinctive orange alloy wheels, quad exhaust pipes, and a "G-POWER" license plate, parked in front of a modern building with large dark garage doors. — Droptops with this kind of performance typically come from exotic outfits like Ferrari and Lamborghini.

On the one hand, milder options, such as the GP-600 software and its required upgrades, are pretty accessible — they’ll set you back around $4,500. More transformative treatments (like the G4M featured above), however, will run as high as $42,000.

If you’d like to learn more or check out the other available packages, you can head on over to G-Power’s website.

About the Author: Gray is an associate editor at Gear Patrol, covering cars, motorcycles and anything else with wheels. When he’s not chasing the latest industry news, he’s probably wrenching on one of many projects. For better or worse, he believes classics make perfectly practical daily drivers.