I wish it would it be possible for game to ask if "current setup should like to be saved". I don't know how many times I have left in a hurry & forgotten to save the setup I've been working on. I can't be the only one.
If that happened, you can find the last used setup in the folder ..\Steam\steamapps\common\rFactor 2\UserData\player It is called 'tempGarage.svm' Copy it and put it into the folder from the track for that it was made, that can be found here ..\Steam\steamapps\common\rFactor 2\UserData\player\Settings Rename it if you want, to better identify it.