Using the Miles Per Gallon Utility

To change the Upper Bound MPG, Lower Bound MPG, and Current MPG settings for multiple vehicles, go to Vehicle Utilities, then the Miles Per Gallon Utility.

You can select individual vehicles by holding down the CTRL button and using the mouse to click on a vehicle. 

You can select a block of vehicles by holding down shift, click on a vehicle, then click on the last vehicle.

Next, click on "Set MPG Bounds".

Enter your desired settings

Click Set New MPG Bounds.