However, the M4 Convertible has never been as popular as the M2, M3, or M4 Coupe. Based on the pre-facelift M4 Convertible, the “G4M Bi-TURBO” kit boosts the twin-turbo 3.0-liter engine to 700 hp. To further beef up the car’s fascia, G-Power added carbon fiber attachments to the corners of the front apron. At the rear, beefy quad exhaust tips with new carbon fiber finishers leave no doubt this isn’t a run-of-the-mill M4 Convertible. G-Power doesn’t provide acceleration figures, but the stock M4 Convertible with xDrive does 0-62 mph (0-100 km/h) in 3.7 seconds.