Originally Posted by bambooshoots
Let's say Plus is about 15 cents more than Regular. It's more like 10-12 cents more here in Texas, but lets use 15 cents for the nationwide average.
A fill up of 20 gallons would be 20gal * $0.15 = $3.00 more if you use Plus, or also $3.00 saved if you use Regular over Plus.
Let's say that using Plus gets you 1.5mpg more than regular. Could be as low as 1, could be higher.
So, 1.5mpg * 20gal = 30 miles more per tank. Most of us get ~18mpg, mixed driving (don't kid yourself with lifted with heavy off road tires).
So 30mi/18mpg = 1.667 gallons worth of "extra" gas if we had used plus. Well, currently gas averages $3.65 (Reg) nationally, so 3.65 * 1.667 = $6.09 more than would have to been spent using Regular to travel as far as when using Plus. So, $6.09 - $3.00 saved earlier when using Regular = $3.09 saved when using Plus.
I looked at it a different way....
Using Chris's original figures of 20cents more (per say) for 91 versus 87.
87 Costs $4 a gallon (for example) He's getting 15.5mpg. That's $.2581 cents per mile.
91 Costs $4.20 a gallon. He's getting 16.6mpg. That's $.2530 cents per mile.
We'll say you're getting 350 miles per tank - which leaves you with a total cost of:
$90.335 for 87 for 350 miles
$88.55 for 91 for 350 miles
That's only $1.79 savings for 350 miles.
If you drop the gas price to $3.50 & $3.65 - then the difference is only $2.06 per 350 miles.
The cost per mile will probably vary a lot between one truck to the other and how we drive etc. You'd probably have to run your own tests to see how your own results end up.