I don't have a save mode on my M8 or my M11. If I make a change on my radio, it saves it.
What I do if I'm unsure about a change I want to make is copy the car to an empty model. Change what you want to on the copied model. If you like the change, make it on the model you race with. The only reason I do it like this is that if I forget what the base point is and I want to go back to what I had before, it's alot easier.