The GazGain guide
Is cheap gas worth the detour?
You spot a station 5¢ cheaper a little further away and it feels like a deal. Often the detour eats the savings — sometimes more. Here's how to decide in ten seconds.
The hidden cost of the detour
Every extra kilometre burns fuel you just paid for. And a detour is a round trip: 4 km extra each way is 8 km total. That fuel comes out of the discount before you ever see your savings.
The math, in one line
Three numbers are enough: the price gap, how much you'll actually pump, and the fuel burned by the detour.
Gross = (nearby price − low price) × litres to fill
Detour = extra km × economy ÷ 100 × low price
Net = gross − detour
An example that surprises
A 60 L tank at a quarter full (45 L to fill). A station 7 km away is 2¢/L cheaper. Your vehicle burns 8.5 L/100 km.
- Gross savings (2¢ × 45 L)
- +$0.90
- Detour fuel (14 km round-trip)
- −$1.94
- Net savings
- −$1.04
The 2¢ discount costs you a dollar more. The pricier station, right there, was the right one.
Three common cases
2¢/L off: often too small if the station is not already on your route.
5¢/L or more: more interesting with a nearly empty tank and a short detour.
Station almost on the way: even a small discount can work because the detour costs little.
The rule, simply
Worth the detour when
The tank is nearly empty (many litres), the price gap is real (5¢/L or more), and the station is almost on your way.
Stay where you are when
The tank is more than half full, the gap is just a few cents, or the station takes you off your route.
Rule of thumb: the emptier the tank and the closer the station, the more the detour pays. When in doubt, let GazGain do the math.
Compare live prices: gas prices in Montreal · gas prices in Quebec City