It might not make numerical sense, but Vin Diesel came back to the "Fast and Furious" series only if a trilogy of new films were part of the deal.  And after the success of "Fast and Furious" and "Fast Five" there's no doubt Universal Pictures is ready to move forward with the sixth film in the franchise they teased at the end of "Five."

Diesel told the LA Times, "I didn't start production on 'Fast Five' until the studio proved they had the treatment for a sixth film. When I returned to the franchise for the fourth film, I envisioned a trilogy following."

A bigger question is whether director Justin Lin will return for a fourth film.  Lin has helmed every "Fast and Furious" picture since "The Fast and the Furious: Tokyo Drift" in 2003 and told the Times he has six projects he's considering as follow ups before another "Fast and Furious."  Lin says, "I want the journey to continue. But I take it very seriously. And I would have to ask a big question: ‘Why would we make another one? What would it be?’ If neither of those things are answered, I shouldn’t be a part of it. I have to be excited, because you get up at 4 in the morning and there’s a lot to accomplish.”

With "Fast Five" hitting $363.8 million worldwide and $500 million in its sights, Lin might not be back, but expect that sixth franchise in April 2013.