Do you drive out of your way for cheaper gas?

In driving home yesterday and, as I unfortunately often tend to do, I was on the search for a gas station because I had let my tank run down far enough that the gas light was on.  Because I was close enough to running out of fuel that I was getting nervous, I just drove into the first station I saw without even looking at the price.  I ended up paying $2.89 per gallon and saw another station half a mile down the road offering gas at $2.73 per gallon.  I have a ten gallon tank and only had a gallon left, so I ended up leaving around $1.50 on the table by waiting until the very last moment to fill up.

I previously had this really negatively affect my wallet a month ago when I was returning a rental car to the airport.  I deliberately waited to fill up until right before I got to the rental car return at the airport.  By way of context, the average price here is between $2.80 and $2.90 depending on which part of the city you are in.  As you may or may not know, if you bring a rental car back and the tank is not full, they charge you a ludicrous price that is typically more than double the going rate for gas wherever you are.  In this case, it was $6.00.  

In any event, every single gas station within half a mile of the airport was selling gas for $3.99 a gallon and up.  So, by not filling up two exits before the airport, I cost myself more than $1.00 per gallon.  I of course had no way of knowing this, but it was a lesson to me to not wait until the last minute to fill up because there is nothing I hate more than having to pay more money than absolutely necessary for something.  

So what did I learn from this experience? I am going to start keeping my eyes peeled for a good price around the time my tank hits halfway empty so I am not stuck stopping anywhere with a pump just because I am about to run out of gas.  

You may think it's a waste of time and energy to worry about saving such a small amount but I would point out that it can add up.  Let's say that each of my wife and I need to fill up once a week.   I have a little car with a small tank but she has an SUV with a 25 gallon tank so we are looking at $6.00 per month or $96 annually for me and then $4.00 weekly, $16 monthly and $192 annually for her for a combined total of $288 for the two of us.  

I know that doesn't wow you as a huge amount that will change your life, but that is still more than $20 per month to spend or save as you wish.  

After that math, I am going to stop the next time I see a station with a cheap price.  

Do you research ahead of time where the cheapest gas around you is?   Do you recommend any particular apps or websites that you find to be particularly helpful?