Thanks. i think FM transmitter is very pleasant to use when you're static. when you're driving is not easy. In paris you have a lot of stations. Use FM Transmitter is useless because each 10Mhz you have one radio. Then there are also a lot of interferences.

Nokia N900 have a RDS Decoder. May be an "AF" function (refer to RDS AF). All cars receiver have a RDS AF function. It's easy to say but I think Nokia N900 should send a code in the FM transmission to tell the receiver to synchronize with it.