The upcoming issue of Entertainment Weekly has a feature article on Henry Cavill’s casting as the new Superman and briefly goes into his audition process for the role.
Seems Cavill wore a replica of Christopher Reeve’s dated outfit from the earlier movies. Cavill had gotten muscular for “Immortals” but had to shed the body for the thriller “The Cold Light Of Day”. Right after that film was shot, the screen test came up.
Cavill recalls: “All I could think was: Oh, god. They’re going to look at me and go ‘He’s not Superman. Not a chance.’ The actor inside me was going: You’re not ready! You’re not ready!”
Snyder says “He walked out, and no one laughed. Other actors put that suit on, and it’s a joke, even if they’re great actors. Henry put it on, and he exuded this kind of crazy-calm confidence that just made me go ‘Wow.’ Okay: This was Superman.'”
The print edition will have a lot more information which will likely come online soon.