Despite the rarefied air of the Academy of Motion Picture Arts and Sciences, its members nominate pretty popular movies for Best Picture. Since 1980, the highest-grossing film of the year has been nominated for Best Picture nine times — three times in the '80s and '90s, twice in the '00s, and once in our current decade. The highest-grossing film of the year has won an Oscar three times since 1980, most recently in 2003 with The Lord of the Rings: The Return of the King. The average winner earns 42.9% as much as the most popular movie of the year, which is to say that the average winner is a broadly popular movie. (If the average stands this year, the winner will be American Hustle or Gravity.)
The top-grossing nominee has been relatively unsuccessful only five times since 1980, and four of those times have happened since 2004, which is likely related to several record-breaking blockbusters (Shrek 2 in 2004, Revenge of the Sith in 2005, The Dark Knight in 2008, and The Avengers in 2012) and not to a more highfalutin set of tastes. The highest-grossing 2013 nominee, Gravity, has so far earned 63.6% as much as The Hunger Games: Catching Fire.
Even after removing the outlier years where the top film was also nominated for a Best Picture Award, the average gross for the highest-grossing Best Picture nominees is 54.6% of the highest-grossing film of the year. Pretty high earners.
The least successful winners, when compared to the highest-grossing film of that year, are Gandhi (1982), Crash (2005), The Hurt Locker (2009), and The Artist (2011).