If a mob vandalized a rental car would the guy whos renting it be liable for some of the damages?

there's one guy we know who's extremely arrogant and he's coming to our city again soon and he always rents a car when he lands near the airport and then takes up the good spots on the street and never leaves because he goes around cheating on his wife and drinking and the car pretty much stays there until he drives back to the airport a week later to leave and he gets all of us angry becuase he pretends to be our friend but its obvious that he doesnt really care and he thinks he's better than us becuase he has more money and success and can get away with cheating on his wife when he feels like it. he parks near to the big sports stadium and this year we were going to put the rival teams flags and stickers all over the outside of his rental car so after people get drunk and come out of the staidium from watching a game they see it and become a mob, would he have to pay for anything where they do if it cuases damage or would he get out of it becuase he's covered by some clause that we're nott thinking of?