My car is bone stock.
Conservative driving nets me 20mpg plus just 'bopping around'. Best highway driving on interstate trip netted 28.7 mpg (that's my best so far) using cruise control as much as possible. These are calculated mpg's not from the DIC - tank topped off at fillups and calculated mpg re. odometer miles driven using 87 octane gas. Keeping tire pressures at optimum (for me): 35 psi fronts and 38 psi rears - cold pressure - contributes to good mileage due to low rolling resistance. Conservative starts from a stop and letting the car slow down naturally when having to stop always helps. Remember that anytime you brake you are absorbing power used to move the car forward, thereby wasting energy (and gas).
Yes, I know that this sounds like boring driving, but the result is better gas mileage, extended brake pad life, tire life, and transmission life. I'm not saying I don't step on it occasionally because I do, but that's when it's 'needed' for whatever reason (you figure that out). I've had hi-performance cars most of my more than 57 years of driving life and still enjoy the 'surge' when the opportunity presents itself, but constantly driving a machine in 'performance mode' because you can doesn't reward you with good mpg
Have fun, but above all be safe.
grandpop09