Sansa Clip best way to connect to car audio

By the way, as to using the USB connection, I may recall that the Clip needs to be in MSC mode for a USB connection (or is it MTP? sorry–try both?) and then, will only read the internal contents of the Clip (i.e., not the contents on the card)–or did I get that reversed as well?   ;)   A little experimentation between the alternatives should answer the questions for you (although it appears that different head units may be different).