Driving Across Town to Save 20 Cents a Gallon
The cheaper sign matters less than what survives the detour.
By The Budget Dad · Published October 10, 2026
Twenty cents a gallon looks worth chasing on the sign. On a twelve-gallon fill, it is $2.40.
That is the first number to calculate. The second is what it costs to reach the sign.
Start with gallons you will actually buy
Price difference multiplied by gallons purchased gives the gross saving. Use the amount you expect to pump, not your vehicle’s tank capacity. A 20-gallon tank does not create a $4 saving if you buy ten gallons.
For an example twelve-gallon purchase, an extra six-mile round trip at 25 MPG uses 0.24 gallon. At $4 per gallon, the fuel for that detour costs $0.96. The $2.40 saving falls to $1.44 before vehicle wear and time.
If the trip adds fifteen minutes, you are spending a quarter hour to save $1.44. You can decide that is worthwhile. Just make the decision with the remaining saving rather than the number on the sign.
On the way is different from out of the way
If you are already passing the cheaper station, the extra distance may be almost nothing. If it requires a special drive, count the entire detour. Lines, difficult turns and a stop that adds significant waiting also belong in the decision.
Check whether the sign applies to cash, a membership or a particular payment method. Compare the same fuel grade. A price you do not qualify for is not the price of your fill.
The fuel-only break-even detour is gross saving × MPG ÷ gas price. In this example, $2.40 × 25 ÷ $4 equals 15 miles. At fifteen extra miles, all the saving is spent getting there. That is an upper boundary before time and wear, not a recommended distance to drive.
Keep an inexpensive station in your regular route when possible. The best fuel bargain is often the one you do not have to organize your day around.