Ok, I have a friend that is dead set on saying the ECU manages the whole car including the transmission. My problem with understanding him, because he does know a lot about cars, is that how does the ECU change the actual gear ratios for a car. I find it physically impossible to understand this because gears are gears and can not be changed without replacing them. Am I correct or is he correct and can you please explain this to me if he is correct. Thanks for the help everyone!