posted by Joe Anaya on October 15th, 2012

Gas is really expensive. Remember before the gulf war, when we used to complain if it went over $2.00 a gallon. Now the price of a gallon of gas sits well over $4, some types $4.50, recently in California it touched $5. One thing I don’t do is drive around looking for cheaper gas. My wife is compelled to find the cheapest gas around. She will drive out of her way to save 10 cents a gallon. If there are two gas stations on my route, of course I’ll take the cheaper one, but I won’t go searching. Not because I’m lazy, but because of math.

Here’s the problem:

Most of the time, when my gas gauge is down to ¼ tank, it takes 10 gallons to fill it up. If I found a station that had gas that was 10 cents cheaper, 10 cents per gallon X 10 gallons, I would save $1.00. At $4.20/gallon, $1 is less than ¼ of a gallon.  My car gets around 25 miles per gallon. So, ¼ of a gallon is about 8 miles.

So based on “gas used to get cheap gas,” if I travel more than 4 miles there and 4 miles back (8 miles total) I am spending more than I’m saving. That doesn’t seem outrageous, if not tedious.

But, I haven’t even mentioned the extra time and energy going out of my way to save $1. My time is worth more than minimum wage, but as a point of reference, $8/hour divided by 60 minutes equals 13 cents/minute. At 13 cents/minute, if it takes me more than 4 minutes to get there and 4 to get back on track, it would take 8 minutes of time and cost $1 of my time, thereby negating any savings.

But wait, there’s more. When I applied that to speed of travel, I got 8 minutes of travel time at 35 mph equals about 5 miles. So, now I’m down to 2 ½ miles out of the way before I use up all my time (at minimum wage) spending a $1 to save a $1 in gas. 2 ½ miles is about ¼ the travel radius as my original range.

If I calculate the gas spent AND the time spent, I’ve spent more than a $1 to save a $1 in gas. 25 miles per gallon divided by $4.20/gal = 17 cents/mile. 17 cents/mile in gas X 2 ½ miles = 42 cents. Adding “minimum wage” time, I’m now at $1.42 spent to save $1.

I started to calculate how far you could go to get to cheap gas including gas spent and time spent but it started to get too complicated and my math skills have slipped since college.

So really, here’s the only equation you need to remember:
$ spent driving to save gas > actual $ saved at the pump.

I know none of this will matter to my wife. She will continue to drive around looking for cheaper gas, and I will continue to cite my math to prove to her how wrong it is.

File Under Jack of all Trades