You have to buy a tuner for your car only. Because when you use it for the first time, it uploads your stock tune from your car to the tuner and flashes your computer with the new upgraded tune in the programmer. It also marries itself to your car and will not work on any other car. The only thing you can do with it is look at and clear diagnostic trouble codes on any OBD2 car. You cant use a tuner that is being used on another car unless that person puts their stock tune back on their car and resets the tuner back to stock form. Then when you use it, it will be married to your car and you cant make adjustments to the stock tune. It sucks, but its the only way the tuner mfrs. can keep people honest and sell tuners. Otherwise, once someone bought one than anyone can use it....and thats not how they work.
Brian