If you spend $1,000 on Gas each year and use a cashback app to save 15% on your purchases, you will save $150. You can choose to pocket that money or use it for something else—like paying down debt, saving for retirement, or spending on other things. If you have more than one car and drive long distances to work and school every day, it's likely worth the time and effort it takes to install an app like GasBuddy or Slice on your phone. Otherwise, try out these apps next time you fill up at the pump.