If you leave and lock the car it doesn’t seem either to sound an alarm to indicate the lights are left on, nor switch them off automatically after some period. I can understand needing to park showing lights but some warning alarm would be useful in case it’s not intentional. Other cars sound a warning if you open the door with lights on.
Is this normal for the S5 to do nothing and gradually drain the battery. I noticed a dash warning message ‘lights on’ when getting back into the car, but sort of shutting the gate after the horse has bolted.