DAB Radio

The only thing I can get (in Brussels) that's listenable to in the car is Radio 4 on Longwave. Reception varies dramatically according to where you are, as it's very prone to interferrance and is very dependant on how well you car radio picks up LW.
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DAB is not an option, as DAB boradcasting range is similar to FM.
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You could dowload radio program podcasts to n MP3 player and play them in the car - most recent car radios allow you to plug an MP3 player in.