The Mercedes-AMG C43 facelift has not only shifted from a sedan to a coupe body style and gained new tech and kit, it's also been given a power bump. Its turbocharged V6 engine now makes a solid 390hp and as ever there's 4Matic all-wheel-drive. How much better is its lap time than the previous model? Narain Karthikeyan gives it a workout at the MMRT.