The Gas Station Detour Trap: When Cheap Gas Costs More

Gas is $3.59 at the station nearby. But the app shows $3.39 twenty cents cheaper two miles out of your way. Time to detour, right?

Maybe not. That 20-cent “savings” might actually cost you money.

The Math Nobody Does

Driving extra miles burns extra gas. Gas costs money. If the detour costs more in fuel than you save on the fill-up, you lost money.

The formula:

Savings = (Gallons × Price Difference) - (Extra Miles ÷ MPG × Nearby Price)

Let’s run it for our example:

• Gallons to buy: 12
• Price difference: $0.20/gallon
• Detour: 4 miles round trip
• Your MPG: 25
• Nearby price: $3.59

Savings = (12 × $0.20) - (4 ÷ 25 × $3.59)
Savings = $2.40 - $0.57
Savings = $1.83

OK, you saved $1.83. That’s actually worth it—but barely.

When It’s Definitely Not Worth It

Small fill-ups: Topping off 5 gallons at 20 cents savings = $1.00. A 4-mile detour costs $0.57. Net savings: $0.43. That’s not worth your time.

Small price difference: 10 cents per gallon on 15 gallons = $1.50 savings. But any significant detour eats that up.

Bad MPG: A truck getting 15 MPG burns more fuel on the detour. That 4-mile detour now costs $0.96 instead of $0.57.

Traffic: Stop-and-go kills MPG. Your “25 MPG” car might get 15 MPG in traffic. Now that detour costs nearly twice as much in fuel.

The Break-Even Point

For any given price difference, there’s a maximum detour distance that makes sense:

Max Detour Miles = (Gallons × Price Diff × MPG) ÷ Nearby Price

Example: 15 gallons, $0.15 difference, 25 MPG, $3.50 nearby

Max Detour = (15 × 0.15 × 25) ÷ 3.50 = 16 miles

You can detour up to 16 miles round trip and still break even. Anything over that and you’re losing money.

But—break-even isn’t winning. You’re spending time and getting zero benefit. For a detour to be worthwhile, savings should be meaningful.

The Time Factor

Even if you save $2, what’s your time worth?

A 4-mile detour in traffic might cost 10 minutes. That’s $12/hour for your “work.” Most people’s time is worth more than that.

If you’re passing by the cheaper station anyway? Fill up there. Going out of your way for small savings? Probably not worth it.

When It Actually Makes Sense

Big fill-ups: Filling a 30-gallon truck tank at $0.25 savings = $7.50. A reasonable detour is easily worth it.

On your route: If the cheap station is on your commute or errand path, the “detour” is zero miles. Pure savings.

Big price differences: $0.40+ per gallon differences sometimes exist between brands or locations. That’s real money.

Costco/warehouse: Often $0.30-0.50 cheaper. If you’re going anyway, fill up. Making a special trip just for gas? Calculate it.

Regional Strategies

Gas prices vary by state. Planning ahead can save real money:

Avoid filling in:

• California (highest taxes)
• Washington state
• Pennsylvania
• Illinois

Fill up in:

• Missouri (low taxes)
• Oklahoma
• South Carolina
• Texas

If you’re driving through, a few extra miles to fill in a cheap state can save $10-20 on a full tank.

Apps That Help

GasBuddy: Shows prices nearby and along routes Waze: Displays gas prices on navigation Google Maps: Shows prices when you search for gas stations

But remember—the lowest price isn’t automatically the best deal. Factor in the detour.

The Real Rule

Within 1 mile of your route: Go for any savings 1-3 miles detour: Only if saving $0.15+/gallon on a big fill-up 3+ miles detour: Rarely worth it unless savings are $0.25+/gallon

Or just remember: your car burns about 15-25 cents per mile in fuel. Every mile of detour costs that much. Is the savings bigger than the detour cost?

What Actually Saves Money

Instead of chasing cheap gas:

Drive efficiently: Smooth acceleration saves 15-30% on fuel Maintain your car: Proper tire pressure alone improves MPG 3% Reduce trips: Combining errands beats hunting for cheap gas Consider the vehicle: Your next car’s MPG matters more than gas prices

A 30 MPG car vs 25 MPG car saves $500+/year at average driving. No detours required.

Bottom Line

Driving out of your way for cheaper gas is usually a trap. The savings look good on the price sign but evaporate in your tank.

Unless the price difference is significant AND you’re filling a large tank AND the detour is short—just fill up where convenient.

Your time and gas are worth more than you think.