The old miles/gallon metric on the efficiency of automobiles has not proven satisfactory to me in analyzing how my present vehicle is serving me. So I've thought of a "new" metric that in the face of rising gas prices makes more sense to me--miles/dollar (Or in the case of ultra-inefficient vehicles dollars/mile).
In this new metric my present vehicle delivers on the order of 24-25 miles/dollar. A comparison--my old vehicle delivered approximately 8-9 miles/dollar. A significant improvement.