Gas

Also little side note, I'm a delivery driver so anything that will give me a little better mpg is also appreciated

87 octane and if its been run on say 91 for a while the computer will learn to use it and may run worse on 87 until learns the 87 all over again, I do however believe that 89 octane is fine to run all the time and may not give you much better fuel mileage it but it may run cleaner and longer on it and 91 will not improve MPG as the engine has low compression designed for 87 and if the computers were not so picky I'd say use a tank of 91 every 3rd-4th fill up but instead the computer will have to learn that its back on 87. But otherwise use 87 and a bottle of fuel injection cleaner a few times a year.