I use 91 in 3 vehicles, average here for 91 is $3.75,

I saw the prices of Diesel, above $4.00, one place I saw it was $4.20. [:-]. So if one were to buy a fullsize truck with diesel, it wouldn't be worth it. At least with teh new Fords, they get crap gas mileage. You might as well buy the gas engine.