I've read that DAB in cars is a bit hit and miss, due the pish poor transmission quality we're lumbered with in the UK. In no way are they anyway near ready to switch off the AM and FM signals yet, as the digital coverage is so patchy.
As for the eighties music, I just play my own off the SD card. I have one folder that has hundreds of 80s 12" mixes in it and it plays for days and days on shuffle!