It seems that after looking at the evidence, that all of the USB radio products are not reliable in a mobile automotive environment and will provide poor quality sound, at best. I tried a few USB options before I gave up.
Then Mitchjs produced a cable and software interface for some HD radios and we can now rejoice

. This is a serial interface that allows you to tune a HD receiver originally designed for an automobile. HD radio and regular AM/FM signals are now pulled in as well as any other tuner and can be used in the Road Runner front end with ease.
Give it a whirl...