I personally think the cost is 3x that (I doubt a fully loaded Semi gets 12mpg), but when you tack that on top of everything you buy it does affect market price

I personally think the cost is 3x that (I doubt a fully loaded Semi gets 12mpg), but when you tack that on top of everything you buy it does affect market prices. I think the biggest cost is in commuting/personal travel. I drive ~19mi to work, 5x weekly, and get 33.55mpg on average (highway&town). This costs me about $19.28/wk just commuting; driving to church 3x costs me $13.37/wk; going to a Bible study in the same area costs me $5. This is $37.65/wk just for scheduled driving in a given week, or about 4% of my net income per pay period (at $3.40/gal which is lower than average prices here at home). Dropping gas prices to $3.27/gal costs me $36.26/wk (barely no change). But if that dropped more steeply, say to $2.50, it'd be $27.71 or 2.95% of my net income. I think that a major drop like that would free up ~2% of everyone's net income. Most people would spend more which would help our consumption-based economy; hopefully others would save it rather than spend it and turn our negative savings rate around.