The fm radio bitrate in the us is dredgingly low. Most stations are still at or around the 98k bitrate. Adding to the fact that the stations can only utilize the frequency assigned to them which further degrades quality and since about fifteen years ago radios no longer go by .5 incriments so now theres more interference.
Radio @ 40 = nearly half the volume of a usb with 320 bitrate songs on it.
An aftermarket fm antenna could potentiall help with the clarity and pickup but quality would still be lacking until radio signals go into hd bitrates.
View my fuel log 2014 Mirage ES 1.2 manual: 36.2 mpg (US) ... 15.4 km/L ... 6.5 L/100 km ... 43.5 mpg (Imp)