Here is how I calculated this claim of mine that it pays to drive around:
one day I was shopping at 4 different stores. I drove to all four stores and tracked the mileage and calculated the gas usage: I spent $3 in gas. But I saved over $65 in my purchases.
Here is the quick formula for figuring it out:
(miles you will drive______) ÷ (Your car's MPG ________)=gallons used
(Gallons used ______) x (Cost of gas _______per gallon)
I drove 11 miles and my car gets 20 MPG. So here is the formula for this trip:
11 ÷ 20 = 0.55
0.55 x $2.98 = $1.63
My shopping trip cost me $1.63. And I saved $65 in shopping on this trip.
Hope it helps fatten your wallet :)