There is a MAJOR issue with the gas filler tube on all Mustangs from 2000 - 2004. The smaller tube they used on these years were coverd with a plastic sheild and two tie clips. The sheild traps dirt and moisture and causes the filler tube to RUST and eventually causes a large hole in the filler tube, which of course means lots of gas on the ground.
I did a lot of research and found a TON of people with this problem. Normally they don't know about it until they see a puddle under their car.
it's not the grommet (although that does have its' own issues).
The reason I am posting this is to save people money! Go under your car now, even when you don't have the leaking issue yet and cut the tie wraps and remove the plastic sheild. If you don't have a hole already, you may be lucky and never have one once this sheild is removed.
If you don't do this, EVENTUALLY, everyone will have to replace the filler tube which is a $120 cheapest replacement part. (found a cheap place, most are 150, or 200 at ford)
I will repost this on the v8 forum as well!
hope this help save some people a little chedda!
Check out the pic (sorry for the quality)