Originally Posted by Jason Rose
Just to play devils advocate here, but what good does an increace of 1 to 2 mpg's get you if you have to run premium fuel that's 20 cents a gallon more than regular?
Glad you asked; if you do the math it works. Rounding down on MadDog's #'s I assumed a 1 mpg increase from 12 to 13 for the city and a 2 mpg increase form 17 to 19 for the highway. I took the prices I saw at the pump here in NY today. $4.09 for regular and $4.29 for the good stuff.
So your fuel costs rise 4.9%
If your city mpg goes from 12-13 you increase your mpg by 8.3% and if your highway mpg goes from 17 to 19 you increase your mpg by 11.8%.
Your not going to retire on that money but depending on mileage it works. If you assume 100,000 miles at equal city and highway you save just over 10% combined, so using the previous prices 100,000 miles without the increase use 6,896.5 gal and costs $28,207. With the increase you use 6,250 gal at a cost of $26,812. You save $1,394 over 100,000 miles. Not a lot but it adds up.
So the moral is if you mod to save mpg don't spend a lot and plan on keeping the truck for a while and the best way to save gas is probably lighten up on the right foot when you don't need the power; that's a free mod.