My experience on this is that if the player really is that ancient that it does not understand V2.3 tags then it also refuses to play such files as the V2 tags are mostly situated at the front of a file and the V1 tags are at the end. The V2 tags are then either interpreted as audio data and played or the player does not play such a file at all.
But let's see if there is any progress on this.
To see what could be a problem with car stereos, have a glance at this thread: