Well I bought a new Locking Gas Cap for my L300 this weekend at my
Saturn dealer. $33 for it, and it works a lot better then the original
gas cap. At least you can tell it is on, after you tighten it down. And
now I have a little peace of mind knowing that my Gas Tank is locked. I
do not know if this will help my gas mileage any, but I am hoping it
will.