The college had a very simple solution.  They towed.  There was plenty of warning with signs, and in orientation programs, and their cars were towed at their own expense.  This might sound harsh, but the reality is that we only had to tow cars maybe two or three times every year.  Once a car was towed, the students would spread the word, complain to their fellow students about their car being towed and the cost of its return.  Once the word spread, nobody would park in the faculty parking lot for the rest of the year.