I don't like this gas pump credit card thing at all.

YY1 said

Kind of a pain to pay cash if you're trying to figure MPG.

That's two trips inside and a guess as to how much $$ to leave at the counter.

Click to expand...

How does paying in cash affect your figuring out MPG??? .

Reset your trip odometer the last time you fill up... Fill the tank again... Record the amount of gallons it took to fill the tank and how many miles on your trip odometer and calculate....

Reset the trip odometer and repeat again for the next fill up....

Using the price of gas is not an accurate way to calculate how many MPG you get as the price of gas changes daily...