Whats the quality of radio? Fm more particular, say I were to broadcast a 320 or 256 bitrate mp3 over a FM radio and then pick it up - what would the quality be? Would you notice a differnce?

Firstly, normal FM radio isn't digital, so it has no bitrate. An MP3 is considered "CD Quality" if it is around 192. I think you would be safe around that.
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Would you notice a differnce?

Yes, you would notice, if you're broadcasting FM with the normal bandwidth. For one thing, there will be interference from natural phenomena (lightning) and man-made sources (power line transformers, for example). This would be true regardless of bitrate.

Also, there is a maximum signal bandwidth on FM (basically, the audio frequencies you can transmit are limited). This is approximated in computer software by changing bitrate, but not very accurately. If you take the audio signal width and multiply by two you get the approximate bitrate to approximate the frequency range that can be transmitted in that bandwidth. Most FM streams are filtered at 15kHz, leading to a sample rate approximation of 30-32 kilosamples/second. Take this and multiply by your sample size (8 or 16-bit, with 16 preferred) and you get your bitrate to approximate it. At 16bit samples, 32 kilosamples/sec, you get 512 kilobit/s.

Okay that sounds a little confusing...I just need a simple anwser for what i'm doing.

I'm buying one of those units that plug into your car lighting, then plug into an mp3 player/laptop/whatever. then this unit broadcasts in your car for you to pick up on over a radio station (200 different channels).

Just wondering if the quality will be decent by doing this, or if its going to be complete shit.

Just wondering if the quality will be decent by doing this, or if its going to be complete shit.

It'll sound like normal FM radio.

The typical MP3 is better quality than FM.