Every car I have ever driven has had one of those silver flappers just inside the filler neck under the screw on gas cap, but my Evo doesnt. Just wanted to know if this is normal.

 

That flapper is keep gas thieves from steeling yer gas. The Evo doesn't have one cuz mitsubishi trolls come out at night and steel yer gas. Why do you think there profits went up?
Seriously, I haven't a clue what that flapper doo-hicky is.