Some questions: how to check MPG? Fuel additives? Alignment (front tires wearing)?

[newagetomboy]

Hi Girls and Guys,

I bought my 2015 Mirage DE from a police auction. It had 17,800mi on it and now going on 29000. I want to know how to check my mpg...That book is pretty thick. In addition it has a wrench next to my mileage numbers. I usually use 87 gas and use a bottle of Lucas Fuel Treatment every month. Should I use it on every fill up? Also should I buy the Lucas High Milage Fuel Treatment instead? What do you all think about Exxon Mobil Synergy? I don't go to Exxon or those high priced gas stations. I am going for an oil change and tire rotation monday. I noticed my front tires are ball on the outer. I do a lot of Rideshare driving around Boston. I will get 2 front tires by the end of the month. Oh it usally takes 7.44 gals after seeing the digital gas gage blink and I read it takes 9 gallons and I don't want to challange that theory....LOL I spend from $16-20 depending on gas prices since I bought it back in March.