I was talking about a 30 to 40 percent cost per gallon difference for a 10 percent gain in mileage. Nothing to do with a tune. A tune is a one time cost and a personal choice.You're right it would be dumb to purchase a tune for the sole purpose of gaining a couple extra mpg. It just happens to be an added bonus. Kind of like getting a damper and reaping those extra hp/tq gains.