i dont know if anyone has experienced this but when i turn the carkit on and the called is routed through the fm transmitter, call volume is set to almost 1 and have to increase volume manually but this is only one time deal; the first call you receive or make after turning it on, would not do the second time and once you turn the carkit off and use regular earpiece you have to up the volume because it is set back to almost level 1.