well ive been told that leaving my car empty is leaving the cars tank to rust from the inside out. i dont understand how this is happening and even if its true or jsut to scare me into filling up my tank while my car sits for a few months.

When a gas tank has no gas in it the surface is exposed to the air which has humidity in in and will rust the surface of the tank. The rate at which this will happen depends on how much outside air infiltration occurs.

it's no myth. gas molecules combine with O2 and the O2 never gets to te metal

If you're gonna let it sit for "a few months" i'd fill it up and toss some fuel stabilizer in it. Sta-bil or something....

well ive been told that leaving my car empty is leaving the cars tank to rust from the inside out. i dont understand how this is happening and even if its true or jsut to scare me into filling up my tank while my car sits for a few months.
I would just fill'er up, and as mentioned add some fuel stabiliser.

well oddly enough this car has already sat for 4 years with a half tank (appox, the gas guage didnt work) so i think a few more months wouldnt hurt it. but right now its dry, ran it dead cause gas guage isnt fixed fully (needs to be calibrated)

our cars have plastic fuel tanks. no rust worries here.

Is that w/ all VWs?

i think it's will all modern euopean cars, i'm surprised modern american cars don't, maybe they do.

the only modern vehicles i see with steel/aluminium/metal tanks are commercial truck (semis etc..) as they need the metal to hold the weight.

The only tanks I have seen rust out, are those that have had water sitting in them.