i can think of a few dozen reasons why this happens. Im a rather frugal person, to take the girl and her 9 yearold and myself it cost 41 dollars for tickets, and another 30 in junkfood. So, 70+ dollars for 3 people to see a movie and have a soda and some popcorn.

Most of the music was hiphop (appealing to a minority?)

Paul Walker and Jason Statham are the only white non-hispanic stars in the movie, and 1 of them is dead, the other plays a bad guy

often if i go to the movies (very rare) i would rather go to a early show since it is cheaper, less crowded, and fits my schedule better

if i wait 3 months i can buy it on DVD and watch it on my big screen at home with pizza and beer for less than 20 bucks

this strangely makes going to the movies, a poor people past-time even tho is cost much more than rental/buying the dvd in a few months its easier and does not require the previous investment of a large tv/entertainment system

when i was younger many of the people who would go to see F&F were "kids" in the racing scene, we would meet before and after and race around town/parking lots and just try to have a bit of fun... i dont recall seeing very many nice cars at the theater due to the cost, and nobody races in my area because of the cops cracking down on any fun we used to have.

I am not trying to make assumptions of minority's and their social or financial standing, however it seemed to play a bit of a role in the demographic of the movie theater I was at in a primarily white area. And with the music and actors almost exclusively being of minority background it would make sense to attract a large non-white attendance.