Enough people have visited the website after googling the phrase "why does Gosling wear the mask" that I figured I'd address the question.
If you haven't seen Drive, don't read this.
Update 4/12/12: check the comments section for expanded details. Big Bubba brings up some good points. The counter-argument to those points involves details that should be in the assessment. But it would also mean totally revamping the assessment which I don't feel like doing at the moment. This is the easy way out. And it also gives Big Bubba the credit he deserves.
Why does Gosling wear the mask to kill Nino?
We can actually turn to Gosling for the answer. In a Rotten Tomatoes interview, Gosling said:
"Basically when I read it, in trying to figure out who would do something like this, the only way to make sense of this is that this is a guy that's seen too many movies, and he's started to confuse his life for a film. He's lost in the mythology of Hollywood and he's become an amalgamation of all the characters that he admires.I could relate to that because back when I was a kid, when I first saw First Blood, it kind of put a spell on me and I thought I was Rambo. I went to school the next day and I put all these knives in my Fisher-Price Houdini kit and I f**king threw them at all these kids at recess, and I got suspended. I didn't hit any kids and I didn't hurt anybody, thank god, but my parents were like, "You can't watch violet movies anymore." They were careful about what they showed me because [movies] really did have a big impact on me. They said I could only watch Bible movies and National Geographic films, but those are really f**king violent, you know [laughs]--but I could see where they were going."
What can we take from that?
Gosling is stating the character is unstable. Confused. Viewing real life through Hollywood's dramatic lens. Which would justify every odd nuance. The Driver is acting how he thinks a melodramatic movie character should act. The Driver, as the violence and drama escalates, is evermore convinced he is living a movie. So, for example, when he's angry, The Driver clenches his fist. But he doesn't just do it once. He repeats the action, over and over. And it's because it's the thing he thinks he should do, the thing a character in a movie would do. I know I mocked this gesture in my initial review--I still think the repetition is funny. But the repetition is purposeful. The gesture is CLICHE. Using it once is cliche. Using it over and over and over again demonstrates how warped The Driver is, how out of touch he is with his own emotions (which is confirmed by his lack of emotion throughout the entire movie), and hints at the fact all of Driver's actions are possibly impersonal and simply mimicry of Movie Characters. But this purpose is lost without Gosling's explanation of how he sees the character. (I can't think of anything in the movie we could use as evidence to suggest The Driver is brainwashed by Hollywood). Likewise, so is the use of the mask.
The mask, if you recall, first appears when The Driver is executing a stunt for some movie. He wears it during the stunt. It's part of a costume. Part of a character.
Now, combine the association of the mask (part of a costume, part of a character, worn during the movie) with what Gosling said about The Driver (he is lost in the mythology of Hollywood) and you can see the symbolic meaning of the mask. And the associative importance it holds for Driver.
Specifically: by donning the mask outside of work, to kill Nino, Driver is obliterating the line between his job and his life, between fiction and reality, between the viewer and the screen. Basically, the act is masturbation. The mask serves no purpose in the actual killing of Nino. Wearing it is purely to satiate some unspoken craving The Driver has.
Without Gosling's explanation, we can only make stabs at why The Driver uses the mask. With Gosling's explanation, we know the character imagines he is living a movie. So...he puts the mask on to better assume his role.
Gosling also said he views this as a superhero movie. In that sense, the mask is like the mask Batman or Spider-man or any other superhero wears. The scorpion jacket is already part of this outfit. The mask and the jacket are stylistically similar to the other subdued, understated superhero flick: Unbreakable. At the end of Unbreakable, Bruce Willis wears a dark, hooded rain jacket and Shyamalan shoots Willis in such a way to lend the outfit the air of Costume. I thought it was really cool. I find Gosling's mask less cool, more funny, too much like The Burger King.
So why does The Driver walk up to the front of the restaurant and just stare at everyone before getting back in the car? I had assumed he was going to burst in and there'd be some sweet slaughter scene, a la V for Vendetta. But, no, there's a cut and suddenly The Driver is in the driver's seat, again. What? Again, wearing the mask, the act of killing Nino, the entire last hour of the movie, is The Driver masturbating. The Driver standing at the door, staring in: he's savoring the moment. He's standing there thinking: holy shit, I'm about to do this--THIS IS SO COOL. It's all a part of living the fantasy.
I'm sure people will make other arguments about the use of the mask. Arguments that don't use outside sources (like Gosling) but that draw from actions in the movie. I don't care. As Gosling said, the only way to make sense of what this guy does is that he's seen too many movies. So that's how Gosling played the character. How Gosling played the character is the root of all the character's actions. He's constantly asking himself "What would a movie character do?"
Just to clarify: The Driver wore the mask for the same reason Trojan added ribs to condoms: to escalate the pleasure.
For further insights into the film, check out this review from Cinema Beans.
If you really wanted to get symbolic, we could argue that the setting of Nino's murder is important.
"What was the setting again?"
A beach, at night, alone...
Usually we associate the beach, at night, alone, with romance. Jaws played on this notion, showing us first the couple at the beach, at night, alone, but interrupting it with a shark attack. Drive is doing the same thing. It's taking a familiar setting, one with concrete connotations, and manipulating our preconceived notions. Where Jaws set up romance to undermine it with violence, Drive is romanticizing the violence. Nino may not be having a swell time ("swell", get it?), but Driver is living out his dream. The scene is a counterpoint to the early "date" with Irene and Benicio, when they go to the creek. That scene was cute, it bordered on romantic, but how romantic can you get with a third wheel (a kid, nonetheless)? Even when The Driver and Irene kiss, there's a third person in the elevator. They are never allowed a private moment of romance (unless you consider them holding hands in the car while he drives a private moment of romance (if so, read a book on romance or something)). Which makes the murder on the beach, where it's just The Driver and Nino, and The Driver is heady with the thrill of it all, the most romantic scene in the entire film.