[1] http://www.intelligentmobilityinsight.com/news/ClB/Porsche-t...
[2] http://archive.fortune.com/magazines/fortune/fortune_archive...
Interests rates are low so getting loans to buy out your competition. In a time when VC money has (relatively) dried up and growth in many industries has slowed your competition are increasingly desperate to keep the lights on. A good few companies are pretty primed to sell right now.
It's not low for German (I'd even argue: for European) standards.
German here; they have ads everywhere; maybe they just spend too much at the moment.
But the parent commenter was worrying about shrinking revenue, not profit. If anything, an overly aggressive advertising campaign should grow revenue while shrinking profit.