Most people will go more out of their way to get cheaper gas when gas is expensive. But if the price...

Most people will go more out of their way to get cheaper gas when gas is expensive.

But if the price difference is the same, say d, is it better to go out of your way when gas is cheaper or more expensive?

If you get g gallons of gas, and you save d per gallon, then how much do you save per trip?

If it costs you x in gas to take the extra drive, how much more does it cost if gas goes up by 1.5, or 2?

So if x is smaller for one price of gas, what happens if the price goes up?