I'm really sick of hearing this pointless monologue. If you are too, here's some simple figures you can toss out the next time somebody goes off on a rant about "which place has cheaper gas."
Let's be generous and assume your car gets 20 MPG driving in the city.
Let's also assume a median estimate of 10 gallons you're putting in your tank.
And gas right now is around $3 per gallon, where different stations around town likely have about 5¢ total difference in price. For the benefit of the doubt, we'll assume the highest price is the one closest to you.
Now, if you shop around and find the absolute lowest price in town, the difference in price will be a total of 50¢.
If you drive even just 2 miles out of your way to get there, you're already losing money just at the pump alone. Round trip = 4 miles, 4 miles being 1/5 of 20 miles, 1/5 of $3 is 60¢, 60¢ subtracted from 50¢ = -10¢. For every mile out of your way beyond that, subtract another 30¢. (3 miles = -40¢, 4 miles = -70¢, 5 miles = -$1, etc.)
In addition, let's assume you make a menial wage of $9 per hour.
If you figure in time as well (for example if you have to clock out of work while doing this) you could easily spend 10 to 15 minutes driving that 2 miles out of your way to get gas, losing another $1.50 to $2.25.
So in total, you're looking at between $1.60 to $2.35 (or the equivalent of more than half a gallon of gas) that you're losing by seeking out a lower price, even with very conservative estimates.
When you go to put gasoline in your car, quit annoying people by incessantly nit-picking about where it's a little cheaper and just fill up at the closest place. In the end, you're actually saving money by not worrying about it.