This weekend I learnt (the hard way) that some Touaregs employ a two-battery setup. One powers the starter, the other powers auxiliaries. I also learnt that VW did not want owners to muck around with the starter battery as it is under the driver's seat and requires the loosening of two "three-square"/12-point Torx bolts. I also learnt that if you try to undo them with a 6-point Torx bit they are very easy to round off. I sense a question brewing...

@Zaid That stinks - one of the first tool sets that I purchased back in the day was a big box of "security bits." Those have reduced those moments of rounded-off-despair for me (but definitely not eliminated it).