Where in the game does it say the vehicles run on fossil fuel? Boomers in New Vegas have a bomber that runs on ethanol so it is logical the BoS in Tactics did the same with their vehicles. The barrels of oil just say "oil drum" again why does that mean it is full of fossil fuel oil? Can't it also just be bio-oil, synthetic oil or full of some other liquid. After all people put other liquids in oil drums. That raider base just simply says "fuel tank" well ethanol is a fuel is it not? There were raiders making gut roat so it isn't to hard to believe they could also make ethanol. Fallout 2 has a quest for you to get fuel for the tanker, does it mean Fallout 2 isn't canon.
People go to great lenghs to explain contradictions in Fallout 3 but they don't think to hard about explaining the ones in Tactics. I guess I am the only one :sadvaultboy: