Here is a PPT presentation on the tax issues of gasoline production. The important take away is the Terminal does the blending from Gasoline stocks(see page 8 ). Now there are different types of gasoline stocks. You don't use car gasoline stock to produce 100LL aviation fuel. Just like 100 grade aviation fuel used during WWII, 100LL has its own blend-stock but like all gasoline products it must be blended at the terminal just before delivery to the customer to make the finished product.
http://www.api.org/meetings/topics/t...ar_Garza-2.pdf