The original poster has a pretty good point that I think got lost. He has an unaltered and completely legal car. He intends to pour straight VO into the tank and blend it with D2. He paid tax on the D2. Why should he be subject to tax on something that just gets him more miles per gallon of D2?

[for those following along, this is where FI completely changes his argument from tax to something else]

FI, do everyone else a favor and get yourself a sticky in this forum where you can make all your arguments in one place. Do you really have the time to rehash and repost these same weak points over and over again?