Sad to say, but with that auto-tranny you've got 3-4MPG wasted just heating the surrounding air, and otherwise trashing the planet, lol. Really sad the lack of technical progress on autos... the engineers got bonuses and high kudos from their employers for making the autos INCREDIBLY CHEAP TO FABRICATE, and nothing else.
(In an informed textbook on the matter, I remember that in 1989, it cost Ford $24 to make the entire AXOD tranny for the Taurus... blown-shell cast aluminum housing, stamped gears, chain drive... yeah baby... lowest dollars/ft-lb... name o' the game... amazing in a way... but not from the consumers' POV... )