Does not work to play a specific song. The manual explains it all. Pages 149 and 150 in the F90BT manual. I don't know which page numbers for the other units. I tried to paste the instructions in here, but the pdf file doesn't let me "copy". Just go to Google and google the model number of your head unit and the words manual and pdf.
I was frustrated with not being able to pick a song too. I have had to resort to saying "Show Artist X". Then select the Album Y before picking the song Z.
In the end, I remind myself I have thousands of songs so it would probably be difficult for the VR to differentiate all of them. It's bummer I can't just pick the one specific song I want to hear, but oh well. I demo'ed Ford Sync and its VR seemed to work better. But, Pioneer VR is OK, I guess.
With the VR, you can pick the artist, album, playlist or genre.