[dcb]

In terms of making power, yes a diesel can probably turn a shot of veggie oil into power more efficiently than a human, assuming it is already warmed up like a human.

But if that power requires a 3000lb rolling cage, then the human on a bike is way ahead efficiency wise.

And it isn't really a valid comparison, you would have to factor in your diet in addition to your fuel bill for the car side of the equation whereas it is only diet on the bicycle side of the equation.