you didn't list if the car is a standard or a super beetle. either way, the gas tank has a vent system. if the vent system is clogged you will get a gas smell in the car, and it will be alot worse when the tank is full. usually the reason the smell is worse when you "hit the throttle" is the fact that the gas inside the tank sloshes around causing the vapors to escape thru the vent system quicker. most of the vent system is located under the front hood, but on some models there is a line that runs from the front, under the pass side running board, to the pass rear fender. there is a canister (or supposed to be) mounted under the rear fender. you can look at places like wolfsburg west, cip1, and such for vent system parts, and thesamba.com has alot of diagrams on how things are layed out, and fixes for such things
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