Use your hands to express yourself. As someone who "talks with his hands," Vin Diesel often uses hand gestures to emphasize his points, especially when he's particularly passionate or exasperated about the topic.
Talk about obscure or silly things. During a 2005 interview with German comedian, Elton, Vin Diesel had a lot to say when the conversation topic turned to The Muppets.
Repeat yourself. In 2006, David Spade featured a montage of clips from various interviews Vin Diesel had done to promote his film, "Find Me Guilty." He was shown giving the same, word-for-word stock responses to various talk show hosts, including Conan O'Brien, Ellen DeGeneres and Jon Stewart.
Speak slowly and clearly. Because he seems to put a lot of thought into his answers and doesn't add a lot of extraneous words during interviews, Vin Diesel comes across as articulate and honest when he speaks.
Be frank. On occasion, Vin Diesel talks about personal aspects of his past. He's publicly discussed some of the struggles he faced on his way to the top, and offered advice to others facing the same struggles.
Say only what's important. In movie roles such as Taylor Reese in "Knockaround Guys," Vin doesn't have much to say until it really matters; then he opens up with a long, meaningful speech delivered in his deep timber (and then usually punches someone's lights out).