Two i listen to quite a bit are..

http://american-graffiti.playtheradio.com/

Currently as i type im listening to The Wolfman Jack show episode 28 on American Graffiti radio.

and, having imported a car from Connecticut, i found..

B1073 Streaming Page - B107.3 FM

These suffer from the usual problems of playing the same stuff over and over and some annoying adverts but otherwise theyre quite good.

I have found that a lot of promising stations with names like Route 66 and American Road radio are not American at all with DJs speaking in Romanian or whatever.

There seems to be a bewildering number of local radio stations in the US to trawl through. I guess from the lack of recommendations that there are not many stations that specifically appeal to the Hot Rodding community. Shame really.. theres a business opportunity for someone