If your vehicle gets 20 mpg with 87 octane at $2.59 per gallon (the going rate here), and you have a 20 gallon fill up, that is 400 miles for $51.80. That is 12.95 cents per mile.

And it gets 23 mpg with 93 octane at $3.09 per gallon (also the go... Login to read more.