Not entering car mode automatically with my device

[Combatter]

Spotify does not enter car mode when it connects to the bluetooth FM adapter I have in my car.  How do I tell Spotify that it should switch into car mode whenever my Android phone connects to it?  Surely it should be as simple as choosing the device from a menu?

"Switch to car mode" is set to "Only in a car" in my settings.

Thanks in advance!

[KYCommuter]

As far as I can tell, there is some code built into the Spotify app that tells it whether or not it's connected to a car's bluetooth device specifically.  For example, spotify does automatically switch to car mode in my Wife's Honda Pilot.  My car is older and doesn't have integrated bluetooth, so I bought an add-on kit that I like very much, but Spotify doesn't recognize it as a car's bluetooth and doesn't switch automatically.  I've even tried renaming the bluetooth device to "look like" the one in my wife's Pilot, but that didn't work either.  

[Combatter]

Thanks. It seems ludicrous that it's not customisable though. It'd be much better if I could identify a bluetooth device as being "my car" to Spotify