computer master reset for best mpg

a gm tech tells me (of the record ) tha he will remove the + & - leads on the battery for 4 hrs and then place them + to- and tape up over night, reconect to the battery in the morning and the take the car out on the highway for a 20-30 min drive. He claims this resets the computer to factory settings as it came new of the line. with the end result the computer is back to the factory settings and the 20 to 30 min drive gives the computer your style of driving giving you back the epa posted mpg. tell me what you think if this. 463:2cents:

You can accomplish the same thing by disconnecting the battery, turning on the ignition and headlights (yes, I know they won't work) and leaving it that way overnight. Most of the VRAM will be erased by then, or at least enough of it will be erased or corrupted so the PCM forces an over-write of the data from factory (ROM) parameters. There may or may not be more than a temporary gain by doing that, since the PCM will eventually learn the input sensors' ranges and adapt accordingly. If one of the primary oxygen sensors is weak, for example, the PCM will eventually learn that weak sensor data and run the engine just as rich to compensate, just as it did before. Any gains would only be temporary, and in some cases the initial programs would result in worse mileage for the first few days of driving.