One thing you can do for your car is to add fuel injector cleaner fluid to it. This will help your gas to run smoother and give you much better gas mileage. This is a type of cleanser that you can get to put your gas tank when you get gas so that it can get the gunk and grease out of the fuel tank. Not getting this for your every so often could hurt your engine because grease and other gunk could get into your engine if it gets backed up enough in your fuel tank.
Source: http://coolcaraccessories.net/best-fuel-injector-cleaners/