most of these things are nothing but resistors on a board... I dont know if it can be done with our cars but if I remember correctly we did this back in shop class, you could measure the resistance over the MAFS(Mass Air Flow Sensor) on a freezing cold start and then throw in a resistor that simulates cold temps thus giving you the increased fuel mileage... just like every one says nothings going to give you any sort of electronic gains other than a remap