There's a chance that this problem isn't related to Spotify but with your car software itself. Did you tested with an alternative music player and got the same result ? If you did (get the same result), you may have to check with your manufacturer and get support directly from them.
If not, that's really odd, could you detail the problem a bit here (for example from where exactly does the error message come from) ?
Hmm yes, that seems like a problem that's more related to your car than to your phone. If you'd like more help from us, could you please give us the model and the manufacturer of your car ? Or you could also contact them directly - I'm sure they offer some support for these kind of things.