That would definitely catch my eye. It might hurt his conversion rate a little from random clicks, but it would help his CTR, and thus lowering his CPC in theory.
That is great! It would probably fuck his conversions, but then again, if he uses really long tail keywords, the people seeing his ads will be looking for whatever he's selling anyways.
they don't show up in google.de and i doubt that google would make an exception for sixt.de although sixt is generally a big spender when it comes to advertisement budgets.
allowing the ad to show up three times and allowing that mis-use of exclamation marks is not really something i would expect google to do.
so, i totally believe in what you said, that this is linkbait only. they do this just to draw some attention to their name again.