At over $80 to fill up my car tank, I wanted to discover whether it is better to commute to buy cheap gas. Feeding a family of six means we go to Costco to buy bulk groceries every 2-3 weeks – on those trips, filling up at Costco is a no-brainer as it is cheaper than everywhere else. But does it make sense to make a specific trip to fill up on gas? This past week, I had two cars on empty, so I decided to make two trips to Costco to fill up our tanks. But was it worth it?

Below is a snapshot of local prices for gas, along with my calculations.

I personally dislike buying gas at the chain gas stations near me as the prices are generally 80¢ to $1.00 more than at Costco. But as I was making the two commutes, it occurred to me that I didn’t really know if I was saving money or not since I had to drive extra miles to actually get to Costco’s gas station. Was I making an honest determination instead of an emotional decision to purchase Costco gas?

Well, once the numbers came out, the non-chain gas station near me only turned out to be $3.02 more than Costco when all the numbers were checked. But even though Costco was cheaper, it took 15 minutes of extra time to get there.  While I might look at the $11 cost difference of not going to Exxon making sense financially ($11 for 15 minutes being effectively $44/hour), even at $3 for 15 min, this only pans out to $12 per hour, which doesn’t even cover minimum wage.

So the next time I have to fill up the car without needing a trip to Costco – my choice is pretty clear. Give my business to my local market / gas station. Even from a time perspective, it is not worth my time taking the extra trip to Costco.