The range on an FM transmitter for a car radio is roughly designed to transmit a radio signal to more than 500 meters away in the FM broadcasting band.
The frequency range of FM (frequency modulation) radio is 87.5 to 108 MHz in the U.S. There might be another band used in other parts of the world, but all FM broadcast bands fall into the VHF range....
It is possible to receive AM signals without an antenna, FM signals, however, require an antenna to be received. The standard FM antenna is around 72 inches for the quarter wave length at the middle...
As long as nothing completely blocks it, there's no limit to how far it travels. But the radio energy keeps getting thinner and more spread out as it travels farther. So the real question is: How far...